# exp. design for a dbl. acting mini. hydraulic cylinder



## hobby (Aug 6, 2010)

Hello everyone,

I have a few mechanical model projects I would, like to design and build,
using hydraulics, so this is going to be a experimental project in designing tooling and such, to be able to fabricate micro-miniature double acting hydraulic systems.

Building a single acting cylinder in hydraulics, is easy because there is no need to have a seal at the top of the cylinder, to contain the fluids, as long as the piston to cylinder fitting, is properly done with good compression, and very minute leakage, at the top.

But designing and building a double acting cylinder is more of a challenge, as I need to cap off both the bottom and top, of the cylinder for fluid pressure to push the piston in both directions.

I have decided I want to make a hydraulic system with a 3/8" dia. steel rod, with an internal bore dia. 1/4", so a piston with a dia. 0.249", and a length of 1/4" can be used and the piston rod to be made of 1/8" drill rod.

I looked at the idea of using my follower rest on my lathe, and makeing the piston and rod one piece, however I want the rod to be over 3", and to get a precise turning cut that way for that long of length could run into bending problems, somewhere if not some inconsistant rod diameter.

So I decide it would be best to use 1/8" precision rod, (drill rod) that ensures perfect dia. along the length of the rod. This means now I need to make the piston and rod 2 seperate pieces.
I thought about threading the piston and rod, than assembling together and then machining the piston down to final diameter. Or to press fit a aluminum piston, already to finished diameter, onto the rod.

I decided to go with the press fit method. This means to keep the 1/8" dia. rod from bending, I would need to fabricate a dedicated pressing jig, that I could utilize on my manual press.

 I look at a project as being not only the finished work itself, but all the tooling and setups needed to be made in order to build and complete the project.
So building tooling is all part of building the final project itself.
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So here is a run down of what I have done so far, in fabricating a pressing jig:
Since this is a work in progress thread, I will give a lot of detail as possible.

The idea of this design is to press the 1/8" dia. 4" long rod onto a piston, 1/4" dia. x 1'4" long, for 
a depth of 1/8".

This jig must support the rod along its entire length, as best as possible, so my design uses a solid rod, and a top plunger, spring loaded.







I start out by machining a 5/8"dia. rod to 4" overall length, measuring the length of the spring and its inner dia. shows I need to maching a stem on the end of this rod 5/16" in diameter, for a 1" length.






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Now to support the 1/8" dia. drill rod its entire length I need to take my time and precisely drill the work piece with a thru hole of 1/8" dia., then finish it with a 0.126" reamer.

So I need to use my smallest 1/8" screwmachine size drill bit, followed by a 1/8" jobber size, finally following that with my 1/8" aircraft size bit.


























Now I'll ream it with the 0.126" reamer as far as it can go.






Before I take the workpiece out of the chuick to turn it around to finish thru with the reamer from the other side, I need to drill and ream for a 0.249" hole 1/4" deep at the bottom of the workpiece.











Now I can turn the workpiece end for end to finish the reaming thru the workpiece.






Now here it is with the thru hole as precisely as possible drilled and reamed through, and the spring that will slide on top of it.
















Now its time to make the top plunger, that will rest on the spring and glide over the base and have a stop after it traveles for 1/8". This plunger will be 2" in length.

Here is the plunger blank machined to final length of 2"






And the drawings for the dimensions.






this will be done in 3 phases.






The first will be a thru hole 1/8" dia. 
after that I will drill a 19/64" hole 1-7/8" deep, followed by a 5/16" reamer.
















phase 2, I need to drill a 1/2" dia. hole 1-5/8" deep.











Phase 3. now bore this hole to a final insde dia. of 5/8" - 0.626" by 1-5/8" deep to make a sliding fit with the 5/8" base previously made. 






Now the parts before assembly






And the jig in it's final assembled stage.











Now a 36" drill rod 1/8" dia. is slid through this jig, to test the accuracy of the assembly.
it slides with no excessive play along the entire length of the drill rod, very presisely done, so this may work in supporting the rod from bending during a press operatiopn.






The way this should work would be, the machined piston will be loaded at the bottom of this jig, then a 1/8" dia. drill rod machined to exact length, will be loaded at the top of the jig, the top of the rod should be just about flush with the top of the plunger cap, that is resting on the spring, now placing the jig under my small manual press, I should be able to press the rod into the piston, for an depth of 1/8" before the plunger hits its stop thereby keeping consistancy with every pressed rod. The spring does nothing more than keeps the cap plunger around 1/8" floating above the base stop. Thereby preventing any bending to occur imediately at the top of the rod where it will be pressed against.

This completes the first part of this project,

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Now time to build a miniature cylinder:

I will use a 3/8" dia. steel rod for the cylinder.
In order to get an accurate inner bore 1/4" dia. it needs to be a thru hole drilled and reamed,
than to cap off both ends with appropriate fittings, I need to drill and tap for 5/16-24 threads on each end for a depth of 1/4"


























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That's all for now, next the piston rod:


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## Speedy (Aug 6, 2010)

very interested!
 :bow:

something I am also interested in making


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## ozzie46 (Aug 7, 2010)

Very nice work. 

 Just a thought, unless you really want to use a press fit, why not use permanent
 locktite? I've not used it yet myself but John Bogstandard and others more knowledgeable than I have used it say its great.

 Anyway I thought I'd throw that out for what ever it's worth.

 Keep up the good work.

 I'll be following along.

 Ron


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## kellswaterri (Aug 7, 2010)

Hi Hobby, why not ''freeze fit'' the piston shaft to rhe piston...make the hole for piston shaft a couple thou under, gently heat piston, spray end of shaft with liquid nitrogen, fit shaft into hole and it wont be moving from there any time soon.
All the best for now,
              John.


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## hobby (Aug 7, 2010)

Michael, Ron and John,

They are all great suggestions, you guys gave me, thankyou,
I definately will keep them all in mind, if my jig doesn't work properly.


Today I started working on the hose bibs, for the cylinder, the tubing I have available is 1/8" inner dia. so I made the bibs, from 1/4" alu. rod, and formed a spigot to put a 10-32 thread at one end.
then drilled a 5/64" thru hole for the fluid inlets.



























Then I began working on the top end cap, the cylinder is threaded at the top and bottom with a 5/16-24 tap. So I measured the tap I used and got around 0.320" for the outside dia. then the spigot on the cap is turned to that dia. for around 1/4" length, later it will be reduced to around 3/16".





























Next I will work on the bottom end cap, then drill and tap for the 2 hose bibs,
I looking at 2 options, for the tube connectors (hose bibs), 
I have aprox. 1/16" thickness on the cyl. walls to tap into, that's plenty in steel.

The first option is to tap for the tube con. straight into the cylinder, or to tap at an angle
by tapping at an angle into the cylinder facing away from the end caps, would direct the pressure onto the piston.
By placing the conn. 90 deg. would direct pressure and fluids more towards the end caps.

So this is something I will be thinking about. As I proceed with this build.


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## hobby (Aug 7, 2010)

The idea of tapping into the thin cylinder wall at an angle did not work, there are heavy leaks as well as too much tube connector inside the cylinder that could interfere with the piston rod, on the top of the cylinder.






I need to redo the cylinder, connectors and end caps over again, and this time, make the end caps to be able to acomodate the tube connectors, I think I will be able to get a good seal doing it that way because I can make the connectors as large as needed without interfering with the piston rod, by using larger dia. endcaps, to accomodate the connectors.


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## hobby (Aug 9, 2010)

Hello,

In order to eliminate any fluid leakages involved in making seperate cylinder and tube connectors to thread into it, I decided it would be best to make the cylinder and connectors as one piece.

I want at least 3/16" tube connector to stand above the cylinder side, so I opted, to usiing a 5/8" dia. aluminum round bar, that would be offset 1/8" offcenter, and then turned down to 3/8" outside dia, leaving 2 places on both ends for the entire diameter of the rod to be machined later on, for the tube connectors.

To machine the cylinder in this fashion, requires a homemade split collet to be able to hold a 5/8" round bar offcenter by 1/8", and have it be used in a 3 jaw, self centering chuck, on the lathe.


























The 5/8" dia. cylinder stock, I'm scribing a centerline, for locating in the collet.











Now I am beginning the process of drilling and reaming the inner bore to 0.249".











No that the cylinder bore is done, I need to loosing the collet and slide the work piece out so it can be machined, this is why the centerline was scribed earlier, so as to have a locating reference for the collet.






The finished workpiece, after the eccentric turning in the lathe.






Now I clamped the workpiece to a V block, and drilled 1/4" deep hole for a 5/15-24 tap, on both ends on my drill press.






And then put it in my micromill-drill to line up and tapped the hole 5/16-24 both ends,
these threads will be needed to be able to put endcaps on both ends, of the cylinder.






And the final work piece (cylinder) before the machining of the tube connectors.






Next I will fabricate a fixture for holding the cylinder blank, either in my lathe or on my rotary table, so I can machine the tube connectors onto the cylinder, where the eccentrics are seen at, in the above photo.


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## njl (Aug 10, 2010)

Hi Hobby, I'm very new to machining. That's an interesting way to make an eccentric part, I'm enjoying your thread and soaking up your ideas.

Thanks

Nick


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## speedhound (Aug 10, 2010)

Hi, this is very interesting, how will you power the hydraulic cylinder will you make a pump? Also what will you use it for out of interest


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## hobby (Aug 10, 2010)

Nick, 
I'm glad your enjoying this thread, as you can see from this, jigs and fixtures are a big part of any build, but that's what make s this hobby so fun and challenging, is figuring ways to machine parts, that from the outset look simple to make, but the preparation for making that part can be longer than making the part itself, I just finished making another fixture for holding the workpiece iin my lathe for machining the tube conectors, but when I went to try it out, it didn't work properly, and I know why, and what I need to do to make this fixture work, you soon discover that machining parts is a lot of trial and error, but through that, is how you learn better ways of approaching the same task.

I went through about a dozen designs and prototype builds for my lathe tapering jig, every fail;ure brought temporary discouragement, but then I would learn from that failure and kept at it until I got what I think is the perfect design (for me) for that bguild, had no problems with it's performance whatsoever, but it took a lot of redoing over and over again.

So this thread may be like that, I may go so far and hit a snag, and have to use a whole new approach, but once I get this working properly, I will then get it down to a science, and post step by step procedure to get the same results everytime.


Speedhound,
The actuation will be with another piston cylinder arrangement, i will have 2 one each to push the piston, in each direction.

If I get it working properly, I will display this one as a mechanical model, with some extra fancy stuff with it working some sort of linkage or something.

If it works excellently, and I have the procedures down to a science, in buildiong these, then I was thinking of designing and building a miniature mechanical type flight simulator, where the airplane would move different directions via the pistons pushing and pulling it, with the mechincs modeled a little like the full size versions you see on TV, and the innernet, for training pilots.

But that is just way on the back burner for now, right now it is just a challenging project in itself to build one cylinder arrangement that works satisfactorily.

Thanks guys for your replies.

Have a great day...


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## hobby (Aug 13, 2010)

These are the 2 failures in making a fixture for holding the cylinder for machining the tube connectors in my lathe.

The first one failed because of a poor design to start with, it was made to act like a split collet to hold the cylinder stock sideways for machining, the failure with it is that this collet will not cinch properly, due to the square walls, milled into the collet.







This second one is a succesful design concept, it works perfectly for holding the cylinder stock in position for machining, the failure is with the size of stock I used to make it, the clamping screws are to close to the area that needs machinied therefor not enough room to bring the lathe tool in from the side to take nice cuts.
The cylinder workpiece got ruined when the screws hit the lathe tool and twisted the workpiece out of center.

However this is the design concept for this fixture I am making, I will use larger stock material, so as to have plenty of room to get proper lathe tool clearance nessary for machining the cylinder blank.






I will now do over the cylinder as well as fabricate a fixture like the one above, only make it larger.


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## hobby (Aug 13, 2010)

I had to redo the cylinder because I ruined the other one.
Which was good, cause now I was able to fine tune the procedures and get this part down to a science.

First I rough the length of a 5/8" dia. round bar to 4-1/2", 






When I drilled and reamed the last time I had to drill and ream a blind hole, because I had the parent stock in the collet, which went further in length than my reamer could handle.

This time I set the workpiece out to around 3" overall working length,






And only drill a center hole for my tailstock center,






That way there is no need to loosen the collet and pull the workpiece out and realigning it as I did the first time.

The workpiece is placed in the collet for all outside machining first, so I mark off the areas needed to be machined,






Then starting out with my cutoff tool I begin to cut these marked out areas to the specific depth,






Then change to a heftier tool, and take almost the entire depth of cut, that way it eleiminates most of the interupted cutting ,due to the offsetting of the center of the workpiece, then after that I take the final finishing cut.












Now I can remove the work piece from the collet, and grip it in my chuck by the 3/8" turned down diameter (center of cylinder workpiece blank), and using a hack saw cutoff the parent stock, which was being held by the collet.






By doing it in those steps, I am now able to drill and ream the workpiece all the way thru the cylinder blank, eliminating any heavy build up of chips when reaming the blank.

So now I drill and ream, the blank to it's proper inside dia., with a thru hole.












Afterwards I can now drill and tap each end, of the cylinder blank.











And again the finished cylinder blank, ready for the next operation. Notice that the hole is more concentric with the rest of the workpiec dia. because of drilling it in my lathe, instead of holding it and drilling in my drill press like I done before.







Next up is to fabricate the fixture for the final machining of this cylinder blank..


......................


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## steamboatmodel (Aug 14, 2010)

Have you considered doing a Tie rod style hydraulic cylinders. It would be much simpler, or threading the cylinder into the end caps, which should house you hose fittings.
http://www.ultrametal.com/advantages-sc.cfm?ID=18&categoryid=45
Regards,
Gerald.


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## hobby (Aug 14, 2010)

Hello Steamboatmodel,

Yeh, my original idea was to put the connectors on the endcaps, but I chose not too, because it would increase the overall length of the whole assembly, I'm trying to scale down my builds to much smaller as possible for me to build, so I have room to display my projects.

However if my present build concept fails, then I will definately look back into accomodating the connectors on the endcaps.

Thanks for your input, greatly appreciated. I like that picture, of how these work, that you posted, looks interesting to study, and maybe try to build a model of it in another experimental project.


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## hobby (Aug 14, 2010)

Ok todays progress, I decided that to make a fixture for holding the cylinder in the lathe, may not be nessary, because that would mean more steps involved to get an acurate setup, so I opted. to build a tooling instead, so all the work in drilling the connector holes and machining the connector itself, can be done all in one setting, in my mill vise on my milling machine.

The tooling I made is sort of like a plug former, rather than a cutter, because it forms a cylinder shape from an already squared shape.

Here is how I made it.

Took a piece of tool steel, 3/8" dia. and after the usual lathe work of getting it prepared (facing both ends), then I drilled a 3/16" hole, about an 1' deep. (this forms the spigot which the tube connects to)
Than followed that with a 1/4" bit for a depth of around 0.1" deep, (this forms the base of the tube connector form),






Lastly in the lathe, I made a taper using a center drill, (to give a gradual entrance of the tooling into the workpiece.












Then over at my mill I milled a flat on both sides to a depth to expose the slots that are formed by the internal drilling. (this gives a lot of chip clearance.











Now a piece of scrap, aluminum square stock 1/4" is in the vise and a cut is made with this tool to see how well it performs in cutting a cylindrical stud.











My camera only takes 30 seconds of video, so the finished workpiece could not be televised, but here it is starting to cut a stud from the 1/4" square piece.






Next I will work on the cylinder and use this tool hopefully, to machine the tube connectors on it.


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## hobby (Aug 14, 2010)

I drill the inlet holes first, this alsop allows me to use these as references if need.






Then I mill away the material on the sides to make a 1/4" square nub, ontop of the cylinder.






Now I use my former tool to machine the spigot on the cylinder.






Once both sides are done, I then return it to my lathe to do a clean up pass with the reamer, to clean up the fragments left by the drilling operation.






Here is the cylinder at this stage, with both tube connectors machined onto it.
















Probably next step would be to start working on the piston and rod assembly or the end caps.


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## steamboatmodel (Aug 14, 2010)

Its now starting to look like a welded cylinder.
Regards,
Gerald.
PS The largest one I worked on was 22" Dia and 7' long, the end caps were threaded on. We had to use a Welding torch to loosen the Loctite


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## hobby (Aug 14, 2010)

steamboatmodel  said:
			
		

> Its now starting to look like a welded cylinder.
> Regards,
> Gerald.
> PS The largest one I worked on was 22" Dia and 7' long, the end caps were threaded on. We had to use a Welding torch to loosen the Loctite



It does give it that kind of industrial look to it.

22" dia. 7' long, sounds more like a canon, than a hydraulic cylinder, ;D.


Now that I have a technique, to machine a inlet port nozzle onto a workpiece, without making them seperate pieces, your mention of putting the hose ports on the end caps, is begining to look more promising, since it's not threaded in seperate, it won't take up as much room, so I can shorten the cylinder to accomodate putting the inlet ports on the endcaps.

Right now the way I'm thinking I could do this, would be to turn down a spigot on a piece of 3/4" round bar, then thread it to the required 5/16-24, that would then leave around 1/4" left of the remaining dia. above the spigot, that can be machined to the required 1/4" square, followed by the former tool, directly on the endcaps.

That way there would be no need to machine the cylinder from 5/8" stock, but now I could use the 3/8" dia. stock.

That would make production a whole lot easier as well as faster, shoiuld I want to build a model requiring several of these cylinders.

I now have the piston and rod assembles, as well as temporary endcaps installed, and tested it out with blowing through the tubes on both ports, and the piston works fine with good compression.

I know I have a good seal on the top endcap, because when I put my finger over the top inlet port, and blow air into the bottom port, the piston moves very slowly, but if I rem,ove the blocking of the top port, the piston snaps out very quickly with little air pressure. That tells me that there is a good seal at the top, because the piston is having a hard time exhausting air as it is moving. So succesful design as far as air preasure working the piston back and forth, smoothly.

Now that I know this design will work, I will look at rebuilding the whole system, by machining the intake ports, as one piece on the endcaps, that will be the next experiment in this build.


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## hobby (Aug 15, 2010)

Time to assemble the piston to the rod using the press jig I made earlier in the build.

















This is the cylinder and piston assembly, with temporary endcaps, 
here I put the top endcap on tight and then drill and ream the 1/8" hole for the rod to pass through.











I decided it's time to run this a test, that's why the endcaps are temporery, to get out any bugs before I do any final machining on the caps.

Therefor to put this through a hydraulic test, I need to make 2 piston cylinder assemblies to act as manual pumps for the hydrauics.

I'm using 1/2" dia.alu.round, and reaming a 3/8" hole, with a 1/4" hole through the top endcap, for the piston rod. This piston rod assembly will be one piece from a 1/2" stock turned to proper diameters.

For anyone NEW to this hobby, here is a quick procedure if you need to make a cylinder with a cap on it and the cylinder bore needs to line up concentric with the hole in the cap, for a piston rod to pass thru, without binding.

First I machined the endcap and threaded it to mate with the cylinder.

Turned down nub for threading.






threading the nub.






then after cutting it off, I wrap plumbers tape around the threads.











Then set it aside and begin machining the inner bore of the cylinder with a thru hole,
drilled and reamed to proper inside diameter.
Keeping the cylinder still in the lathe I tap the mating thread into the one end of the cylinder.

Now with the cylinder completed on that end, keeping the cylinder still in the lathe, I screw on and tighten the previous ly made endcap.






Then I do all finish machining to the endcap, such as facing it to length, and any decorative turnings to it. In this machining process the endcap continues to tighten more and more, as the cutter makes contact with it. Also if the 2 pieces weren't threaded straight, when put together like this they can have any iregularities machined out, so it all ends up concentric.






Now after all the machining the profile is done to it, the endcap is as tight as it will get hopefully giving a good seal, now its time to drill and ream the hole through it the proper dia. for the piston rod to pass through.











If done properly the rod hole should be very concentric with the cylinder bore so as to have smooth piston movement, with a fairly good seal with the rod and cap.






The before and after of the top cap and cylinder assembly.






After both these cylinders are to this stage, I can then put the cylinder back in the lathe, with the bottom sticking out to tap the threads for the bottom caps.


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## kcmillin (Aug 17, 2010)

Hobby, I love the project, and your thread is great, very informative.

 In the past I dabbled with hydraulic cylinders for some R/C applications, and my biggest pitfall was the hoses I tried would have some expansion and take away movement from the cylinders. I guess a rigid line would work best. 

My question is what are you going to use a hydraulic line? DO you know of any high strength hydraulic line down to 1/8 inch inside diameter?

Kel


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## hobby (Aug 18, 2010)

Hi Kel.

At the moment, I'm using the plastic tubing, pretty much the kind for fish aquariums, air tubing.

That's the kind of tubing I used for my lift table, I don't recall having any kind of issues with that table project using that tubing, If it was expanding and causing problems I really didn't notice anything, however your RC projects may need more precision in its movement of the piston, while my table project was more like brute force just to get it to raise up.

Have you tried "smallparts.com", they may have the kind of lines your looking for.

Thanks for watching my thread.



Hello to everyone,
Update in my build thread:

As I said in my earliewr posts, my work in progress threads go from one idea of build to a completely different approach until I hit the right combination.

I hope this thread isn't becoming confusing, with all the detours I take.

With that said, I am now REDOING AGAIN the whole cylinder arrangement, the reason for that is, when I did my last cylinder, it came out great, However I clamped the cylinder after it was hollowed out just a little too tightly in my V block to machine the tube connector, and put a dent on the inside that will not ream out, the piston stilol works fine, but now and then there is a small catch in that area.

But as I was thinking about the best way to build these should I want to build several, I thought about using 3/8" dia. alu. rod, for the cylinder, and machining as one piece the tube connectors onto the end caps, that way less iterupted cutting on my lathe for the length of the cylinder, and use 3/4, to 7/8 dia. rod for the endcaps, with no offsetting in the lathe but all machining would be done on the mill for the tubeconnectors.

These are ideas I'm kicking around right now.


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## hobby (Aug 20, 2010)

To make the cylinder I used a piece of 3/8" alu.round rod.
I drilled and reamed it and tapped both ends 5/16-24 threads.

Now I turn my attention to the endcaps, I'm using a piece of 1" dia. alu. rod, 

After dressing it up (face turning), I then machine a 1/4" spigot.
 on the end







to use a die and make 5/16-24, outside thread, which will mate with the tapped ends on the cylinder.







Now a relief cut in the workpiece., to give clearance for ther form tool.






Now I machine down the 1" dia. to around 7/8" dia. This then will leave aroiund 1/4" material above the 3/8 " cylinder.






At my mill I begin the process of drilling the inlet hole and the machining off the sides and later the bottom off this.






Now using the forming tool I form the tube connector.






here it is right after the machining of the connector.






Bandsaw the right amont off.











Now I wrap plumbers tape around the threads and screw it on to the cylinder, and place the whole assembly back into the lathe for machining the finishing on the endcap.
















Now drill and ream for the piston rod.






Still have the bottom cap to make yet.
But here is what it looks like with the tube connector machined into the endcap, rather then the cylinder.











Next is the making of the bottom endcap.


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## ozzie46 (Aug 21, 2010)

Nice work. Your trials and solutions are very informative.

  Ron


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## hobby (Aug 26, 2010)

Thankyou Ron, for the nice compliment.


Here is a test using air only, and it is coming from a small solder sucker, bulb, 
I hooked the line up to the bottom cap inlet only, and left the top inlet open, to the atmosphere.

I have a lot of extra hose around 3ft. so this is a good test to see if a minute amount of air through a long distance of hose will have a positive effect on the piston, in the cylinder.

To my surprise, it has a very positive effect, also I never expected this, but when I let go of the solder sucker bulb, the vacume suction of the bulb pulls the piston back in again, there is a good seal with the piston, and rod, and the cylinder and top cap, where the rod passes through.

I can vary the amount of piston movement both directions, with very positive controle of squeezing the solder sucker bulb.

This test proves that the build is succesful so far, at least with air.

I need to finish the bottom endcap, then start working on the pistons and endcaps for both manual pumps, that I started earlier.

I'm hoping ,if I get this working properly, with water, or air, to move the piston in precise movements, to be able to make some sort of a dialing mechanism, where I could dial in on a wheel, left or right, which would push on levers for each manual pump, to actuate the piston in small incremental movements in relation to the amount of rotary turns on the dial..

That will ttake a lot of experimenting, and design work, which is what this project is all about.

Here is a video of the piston movements actuated by the solder sucker bulb.
The movements are kind of fast and non precise, as I was just trying to keep the video as short as possible for the upload time.

http://www.youtube.com/v/Wba8TlYf-vM?fs=1&amp;hl=en_US


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## ozzie46 (Aug 26, 2010)

Thm: Thm: Thm: Thm:

  Ron


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## hobby (Aug 27, 2010)

Thanks for the thumbs up Ron...

I'm making the bottom endcaps for the manual pumps, cylinders,
again the spigot will be formed on the cap as one piece, however this time the spigot (tube connector) will be elevated at 45*, so as to accomodate the tubing in more of a vertical configuration to the cylinder, rather than perpendicular to it.

I started out with 1" dia. alu. round stock, cut and machined to finished length.






Then a nub is machined onto it and threaded for 7/16 20 to mate with the bottom of its pump cylinder.






Then I center the spindle in relation to the center of the workpiece.







Vice tilted to 45*
First machine a flat that will be the top of the spigot.
Now drill the output hole for the spigot later to be machioned. Also this hole serves to line everything up as a reference, later when I need to get back to center for the final forming of the spigot.











Now I drill 4 reference holes to guide the 1/8" milling bit to rough shape out the spigot.






Now with the endmill, mill out the rough shape, of the spigot.






Back to centering up the workpiece under the spindle using the drilled hole as reference.






Now the finish forming of the spigot.











After milling out all the material around it.
















And with the manual pump cylinder screwed onto it for a test fit.






Testing it's performance with the hose connected.






Next is to finish the other pump, endcap base, then start working on the pistons and such for each manual pump cylinder.


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## kcmillin (Aug 27, 2010)

Nice progress Hobby. I Like your methods.

Is that a home made cutter you used to make the spigot?

Kel


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## hobby (Aug 28, 2010)

Thanks Kel:

That is a homemade cutter, it's more like a corner rounding from tool, I machine the spigot to a rough 1/4" square, then proceed to use this forming tool, to make it round.

Please see post #14 page 1, I give a little detail of how I made it, with a quick video of it being used.
In the video I used fast speed, because my portable caqmera only takes 30 sec. of video, so I tried to get it working as fast as possible, but when I normally use it, I have it on low to medium speed, and very carefully plunge it onto the square post, a little at a time, until it starts forming the shape then when it gets to that point, it then cuts almost like butter, very easily and quickly, almost feeds itsself into the work.

Thanks...


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## hobby (Sep 3, 2010)

These are the parts so far, the further rightmost set of parts are the hydrailic cylinder and piston assembly itself, the left sets are 2 identical manual pumps, seperated into there individual components.






This is a rough mockup of the assembly for testing purposes only.






This is the first in several fine tunings that will be needed to make it as leakproof as posible.
First I checked to see how a rubber gasket glued to the top will work in sealing the water from leaking out the shaft holoe. It works well except that the leakage occured at the contact point of the cement itself, lifting the seal.






So I know that I coulod make a rubber o-ring gasket to fit snugly around the shaft to prevent leaking. 

So the next process in this is to redo the top endcap, where I will make a screw fitting to encase and crimp tightly a rubber gasket against the top openeing of the endcap, where the shaft comes thru.

Also I noticed that there was leaking occuring around the cylinder and top encap connection, where the two screw together at, This is mainly due to the fact that I machined the square portion to close to the thread,






 which gives very little surface area to make a seal between the cylinder end and the cap base.






So now I will make accomodations for these two failure points in the top endcap.
That's updated for now...


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## kcmillin (Sep 3, 2010)

Hobby, great progress.

If you use a thick oil, like hydraulic fluid or gear oil you will have a better chance of your seals sealing. This is because the molecular structure of water is very thin, where as oil molecularly thicker and will be less likely to leak.

Just a thought.

Kel


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## hobby (Sep 4, 2010)

Thanks Kel,

That's an excellent suggestion, the thought of using oil crossed my mind several times, on account of it being thicker, but I kept dismissing it, because of the mess it would make as I am testing for leaks, 
But,seeing someone else suggestion it also, has made me think that is the best way to make this work.
I'll use water to do preliminary tests, but oil it is when it comes to the finished working model.
Again thanks for the suggestion..I needed that.


Ok the process of remaking the top endcap, the idea is to make it 2 seperate pieces consisting of the endcap base and a screw on cap to contain and keep tight a rubber gasket of sorts.

Start with the workpiece being machined for threading and a relief for the hose connector.






then cut the top half off to make the 2 seperate pieces to this part.






Now I machine a nub, and thread it for mating with it's own cap. (gasket container)






The workpiec screwed to the cylinder. I accomodated more surface area for the cylinder end to bear against. Unlike the original that had very little surface bearing.






Now the gasket container is roughed out and threads taqpped into it, to connect to the top of the other workpiece.






both workpieces machined and ready for a dry fit.






and dryfitted together.






Now after milling the connector into the workpiece dryfitted together again.







Now return the whole cylinder assembly back into the lathe to do the final machining of the gasket container cap, as well as the drilling and reaming of the piston shaft hole.
















Without the rubber gasket installed yet, this is the sequence of the dryfitting of the 3 components,
the gasket container, to the endcap base, and the whole endcap assy. screwed onto the end of the cylinder.





















And with the piston inserted into the cylinder and the gasket container offf, this shows the assembly before the gasket is inserted.






The next procedure will be to fabricate the gasket and insert it into the container, screw this tight onto the endcap base, using a sealant of somesort on the threads, then return this to the lathe to drill an undersized hole through the gasket, to allow a tight forming fit around the piston rod, when it is finally assembled.

Thats all for now...


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## hobby (Sep 5, 2010)

Yesterday I made a new bottom endcap, to match the new top one I made, so it now has more surface area for the bottom end of the cylinder to bear against for a better seal.

Today I started the permanent assembly of the endcaps to the cylinder.

I started with the top endcap and made a reference mark





Then put a sealant caulking at the base of the cap, and put loctite on the threads and proceeded to screw it together.











Then did the same on the bottom cap.
Making sure I have the piston inside the cylinder before assembling it all together.











Set it aside for the loctite and the caulk to setup properly.






Also caulked and loctited the 2 bases to the 2 cylinders for the manual hand pumps as well.

Next will be to make the gasket for the top cap and install that together, then do some test runs.


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## hobby (Sep 6, 2010)

Hello everyone, another update:

I first used water to check for any major leaks, and where the cylinder and endcaps are fitted, there are NO leaks everything everything is sealed nice and tight, the only leaks I was getting, was around the top endcaps on the manual pumps, these endcaps cannot be sealed permanently, so as to load the fluids into the cylinders.

However the leaks were only occuring when substantial pressure was being placed on the hydraulic piston when the piston was being forced in the other direction.

Since the leaks were rather small, I was convinced that the sealing of leaks throughout the whole assembly was good enough to go with the 3in1 oil, because of its thicker consistency.

What a difference it made, the oil is sealing the gap between the pistons and there respective cylinders, and there are NO leaks any where throughout the whole system, including the manual pumps.

The first video is a quick demonstration, of the hydraulics working with no load, static mode.

"http://www.youtube.com/v/NbMH701jm4A?hl=en&fs=1
This next video is demonstrating the hydraulics working under a load, pushing a set of solid 1-2-3 blocks.

Again under this loaded condition no leaks were to be found.

"http://www.youtube.com/v/dHPxgw_YhnE?hl=en&fs=1"></

Now that the design has been founded for this build, it's time to start working on the actuating system for the manual pumps.

Then the chassis to hold everything together as a working model display.


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## kcmillin (Sep 6, 2010)

Great Job Hobs!!

Glad to hear everything is sealed nicely, it appears to work fantastically.

What is the ratio of the pump piston diameter to the working piston diameter? 

OK I'm just thinking out loud here, but you could simplify your setup by using 2 cylinders instead of three. If you make another double-acting cylinder, like the one you have as the working cylinder, it would serve the same purpose as the two pump cylinders. Just a thought.

Kel


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## hobby (Sep 6, 2010)

Hi Kel,

The ratio of pump to working piston dia. is 3/8 : 1/4

I like that idea of using a second dbl.acting.

That would be a complete circuit, requiring only one lever, to push in and out, while the driven piston inverts the output , thereby making a continuous loop, like a alternating current.

Since I have all the materials already into this build, I'll continue with these 2 cylinders, but I think your idea of using a master-slave cylinder config. would be a great way to build another project using hydraulics.

As always Thanks again for the input.
Greatly appreciated..


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## hobby (Sep 6, 2010)

Hi Kel again,

Those 2 cylinders were just made to test the concept of my hydraulics, so I could always use them for test pumps, with other projects,

I like that idea of using a master cylinder, so much, that that is going to be the next part of this build to design and build a master input cylinder, to drive the second working cylinder.

Thanks again...


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## kcmillin (Sep 6, 2010)

Thanks Hobs, I am very interested in your project, and you are doing a great job of all the hard work. I have been pondering the idea of miniature hydraulics for awhile now, and I am glad to see someone els trying to figure it out too.

Well Done Thm:

Kel


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## njl (Sep 8, 2010)

Looks like your are going great guns Hobby, I've really enjoyed following your progress.

Nick


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## Jared (Sep 8, 2010)

I've been enjoying this, too. As an equipment operator I've spent a lot of time making hydraulic cylinders go back and forth and I've thought about building models like this. 
 If you wanted to get real fancy, you could build a gear pump and then an engine to turn it. Valves might be the hard part.


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## hobby (Sep 10, 2010)

Thanks Kel, 
I think I got the cylinder and endcaps down to a working science, now, where any kind of failures should now be only in the area of production, machining the parts or just plain stupid mistakes, but I think the design is pretty close to being failure proof.

Thanks Nick,
 for following along, and replying, it helps me have incentive to continue on when the design and build process gets a little rough at times.

Thanks Jared,
 for the reply, your suggestion of using a oil pump is very well appreciated, it has got me thinking in that area once I get this master-slave system built, ( which credit goes to Kel, for that very good suggestion), then I might look into designing a auto pump system, starting out crude, and working up to an elaborate system, if I have the tooling, the knowledge will come from studying up on the subject of oil pumps, and getting an education, of it's working principles then I'll try to take it from there.


OK. todays progress.

With the top endcap on the working (slave), cylinder, I made a gasket cap to hold the rubber gasket tight to the cap base. However it was not the best way to approach this, because I drilled and reamed a blind hole, so the fit is not perfect it had to be packed in order to make enough contact with the gasket to keep it tight to the cap bas threaded stub.

Learning from that mistake, Since I now need to build the master (driving) cylinder with the same configuration, in order to be able to actuate the piston.
I decided to make the top gasket cap in 2 seperate pieces, the first piece is a ring threaded all the way through, this ring will screw onto the cap base, and contain the gasket, the second piece is a threaded plug, that will screw tight into the ring compressing the gasket onto the cap base.

Here is the mockup, before the actual machining process, the piece on the left is the actual endcap base piece, the second is the ring container, the third is the gasket plug.






preliminary fitted together.





The usaul machining of the spigot, also these endcaps will have a hole drilled and tapped so as to be the oil filler holes for both the front and back of the piston.
So a hole is drilled and tapped 90* from the spigot, in this process.





















Now the cap base anf the ring are fitted together for machining the outside dianeters to respectrive values.
















Then the plug is screwed on and outside machining done to it.






And now the whole assembly is drilled and reamed for the piston rod dia.







Now the whole cylinder assembly is removed from the lathe, and the endcap assembly minus the plug, is permanently sealed and screwed together.











Now using a aligator clip rubber cover, I was able to cut out a rubber gasket, to fit inside the ring on the endcap. then I tightly screwed on the plug to compress the gasket into place.
Afterward I returned the entire assembly back into the lathe, to drill an undersized hole through the rubber gasket.





















Now using my surface plate and guage, I locate the holes to be driloled on the bottom endcap,
by lining up the top encap spigot, and oil fill hole.






The bottom endcap is machined with a spigot, and oil fill hole, and machined in the lathe to final outside dimensions.






These are the obsolete parts that are in perfect condition, but were replaced for upgrading.






This is the new upgraded system and it's new parts.






Next will be work on the oil fill plugs and piston and actuating device for the master cylinder.


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## hobby (Sep 12, 2010)

OK, the last part of this experimental project.

This is the oil fill reservoirs, for filling the master cylinder, on both sides of the piston.







And the oil caps in place after filling.







Here is a quick working demonstration, using a master-slave system.

http://www.youtube.com/v/m0DMe5CLdwk?fs=1&amp;hl=en_US

This is the last installment for this thread,
I set out to experiment in seeing if it is possible to design and build a double acting hydraulic cylinder, with minimal leaking exspecially where the piston rod exits out the cylinder.

What I've found is that a good seal can be made, making a rubber gasket, to fit tightly around the rod, and containing it using a 2 piece system consisting of a threaded gasket containing ring, and a gasket compression nut, that screws onto the ring with a thru hole to allow passage of the piston rod. Then this assembly screwed onto the top endcap.

Also I learned that making endcaps on both ends of a cylinder, is better, so as to get an accurate reamed thru hole through the cylinder, rather than a cylinder with a blind hole.
A blind hole makes it difficult to get an accurate reaming all the way to the bottom, due to chip build up during the reaming process.

Also making the hose connectors, on the endcaps seem to work real well for a good non leaking fit with the cylinder, as well as a good thread locker and some sort of sealant for all the permanently attached threaded fittings, such as endcaps, and such.

For long length piston rods, I found it's best to make the piston seperate and using drill rod for the piston rod.

As far as making the hose connector (spigot) as one piece with the cylinder or the endcap, is a sure way of keeping out all leaks, however I'm fully convinced with the proper surface area bearing points, that a seperate spigot, can be screwed into the cylinder or endcap, or any other workpiece, provided it is fastened in ,using a threadlocker, and a sealant of some sort.
Or even a gasket of some sort. But threadlocker seems to be the key ingrediant to this 2 piece spigot system.

Thankyou to everyone, who contributed ideas in making this a succesful experiment,
and thankyou to everyone who has been following this thread.

Thankyou, and God Bless...


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## ozzie46 (Sep 12, 2010)

Thanks for the journey. You have given me lots to digest and think about.
 The cyls look great and work well.


  Ron


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## kcmillin (Sep 12, 2010)

Well Done Hobs, and a very fine thread. :bow:

SO........what are you going to do with them now?

Kel


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## hobby (Sep 12, 2010)

kcmillin  said:
			
		

> Well Done Hobs, and a very fine thread. :bow:
> 
> SO........what are you going to do with them now?
> 
> Kel



Hi Kel,

Thanks, for the compliment.

 My original idea was to try to model, one of those full size flight simulators, that pilots train in, I found some pictures on the innernet, that show the hydraulic cylinders, and I thought it would be a good machining challenge to make a miniature model of one, and see if I could get it to work mechanically. 

I just did a google search on "toy hydraulics" and I wish I would have thought about this sooner, because there is a whole slew of you tube demonstrations that these kids use syringes, for the hydro. cylinders, and they use just the push and pull of the piston movement to carry loads, the piston of the syringes has a good seal due to the rubber piston, that the forward pressure and the backward suction is enough to draw the working pistons when loaded, so there is no need for a 2 tube system, if the piston is machined acurately.

So if I model this flight sim. hydro. system, I will use the one hose method, which will give me an oppurtunity to machine six pistons and cylinders and lap every one to a somewhat perfect seal, to achieve the ability to make my cylinders work under load, double action. That for me in itself will be a challenge.

The major challenge in this project will be to make a miniature joystick of some sort, that will work the manual pumps, in a controlled manner. If its possible, 

 Even though it wouldn't be much of a enthusiastical mechanical model to watch, it sure is going to be a lot of machining challenges to get it to work properly.

My enjoyment in this hobby is the designing and building process, more than the displaying of each model.....  A simple looking model, but a challenge to build.

Thanks again...


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## hobby (Sep 12, 2010)

ozzie46  said:
			
		

> Thanks for the journey. You have given me lots to digest and think about.
> The cyls look great and work well.
> 
> 
> Ron



Thankyou Ron,

I appreciate the compliment.


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## Speedy (Sep 14, 2010)

love the videos, you made some very smooth cylinders 
thank you for sharing, you have put out plenty of ideas and I think I would like to give it a try!


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## zeeprogrammer (Sep 14, 2010)

Very cool. It does give one something to think about...miniature hydraulics.
I notice you have a mini-lathe like mine. Did you make any kind of adjustments to it?


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## hobby (Sep 15, 2010)

Thanks Michael,

If you do give it a try, please keep ua up to date on your progress, it would be neat to see what kind of projects that can be done with this.

Even if hydraulics is not used, a very well fitted piston to cylinder, arrangement, would make real good projects in pneumatics as well. It wouldn't be as messy, (oil leaks).

Thanks for following aloing and posting.



Hi Carl,
I didn't need to make any adjustments to my lathe,
I got my lathe and micro mill, both around 2002, And this homeshop machining was all new to me, 
And I thought it was already workable right out of the box, so I never knew anything about attempting to modify it or rebuild it, until I discovered the forums out there on the net, then I started to hear all kinds of things about these needing to be rebuilt to work accuratly.

I must have gotten one out of a good batch, or else I just adjusted to it's inherent inaccuracies without even knowing there were such a thing for this tool because I started using it literally right out of the box, I didn't know any better, at the time, I assumed these tools have to be in tip top shape for accuracies, because there machining tools. What was I to know about if a machine tool is working properly,  I mean all this was totally new to me.

Even now with the knowledge of these things I still do not see any need for any major adjustments for my lathe.

Did you make a manual handle attachment for your lead screw?, I did, and it is a very convenient modification, especially when I'm setting up a distance for my cut, I lock the carriage to the lead screw, then I set up my dial indicator, and start turning the handle to advance the carriage in the thousands of an inch very precise movement rather than the abruptness of the handwheel on the carriage. and then set the carriage stop. 

Do you do a lot of taper turnings? If you do , and find your having problems adjusting the compound slide to get the proper angle, or you need to use the tailstock center for longer pieces and the tailstock gets in the way, let me know and I'll post a picture of my taper attachment (homebrewed), (In the tool section of this forum.)
that could give you an idea of how to avoid these problems.  This jig replaces the whole crosslide, and locks into one position on the bed, and all angle adjustments are easily done by just loosing a bolt and turning a turret to the angle needed then retightening the bolt, the tailstock can be used without it being in the way because the carriage remains in oneplace the turret moves on its own track down the length of the work.

However this is only if you do a lot of tapering, and you want a more accurate way of setting the angles.

Thanks for posting...


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## kustomkb (Sep 15, 2010)

Nice job on your cylinders Hobby!

They work great. Lots of good ideas there.

A couple of those with your scissor lift might make a nice work stand for my bike ;D


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## hobby (Sep 15, 2010)

Thanks KustomKB

Sort of like a team effort, you build the bikes and I'll build the scizzor jacks to display them on.... ;D

I started going over your thread AGAIN, and when I got to reply 36, you showed a video of you fabricating outer rims for the flywheel, and I seen how many parts you made thus far, and then as I watched that video, I realized I was doing it all wrong, 
no wonder it took so long for me to do my projects, so I seen how you did the tailstock drilling, and I thought :noidea: ok, I'll run the drill in just as fast and see if that speeds things up for me, soooo I spun the handwheel as fast as I could, and the drill bit the work, and then bang...broken drill bit, I tried this several times, but ran out of drills. I think maybe I need stronger drill bits ;D

So then I tried to do a facing cut as fast as you did, would you know the lathe bogged down and then bang...I kept breaking my cutters. :wall:

I tried to measure as fast as you did, but I couldn't see the numbers they were like a blur going by,

I don't know, you really amazed me at the speed you work

As for me, I guess I'll go back to my old way and take hours to machine parts, yeh I know, it's a cop out,
but what da you do,,,I guess some people got it and some people don't , I guess I dont got it (the speed). :big:

Any way 
thanks for the complement.


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## zeeprogrammer (Sep 15, 2010)

Thanks for the reply hobby.

I don't do very many tapers. Well none really...I think I've set the cross-slide to an angle twice...once for cutting the rims on my little loco...and one other time that I can't remember. ;D

A manual crank sounds more interesting to me than the motorized version. I know what you mean about the abruptness of turning the carriage wheel.


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## kustomkb (Sep 15, 2010)

Thanks Hobby, but you know what your problem is, my alter ego is Flash Gordon. If I screw up I just spin around the world a few times really quickly and time travels backwards. Then I tell myself to watch out, say thanks, and proceed with caution.






You guys mention the abruptness of turning tapers with the compound, I made a little handle, a stick with 2 holes and a handle, to extend the radius of the handwheel which I find helps give a little more control and smoothness when turning longer tapers. If you have the room to swing it. even a 1/2 inch will help.


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