# Little Demon V8 - helpful hints (hopefully)



## Carbuilder (Jan 2, 2022)

This will be sort of a build log, but hopefully with a difference.

Here is what I am hoping this thread will provide. This will not be a normal build thread with many pictures of my finished parts. This will be more of a show and tell as to how I made the parts; how they were set up in the machine and how I made them that may be different from how others did it. And most important, I’ll show the mistakes I made on some of the parts and how I repaired them without having to machine a new part.

I’ll put an introduction to myself and my shop here, so you can skip this part and get to the meat if you like.

I bought my first semi-serious piece of machine shop hardware many years ago. It is a 3-in-1. Yes, one of those machines that everyone hates, recommends you never buy, never use, and really should be replaced with a full-size mill, lathe, and drill press. This is a Busy Bee unit (me being in Canada); same thing as the Grizzly G9729. Over the years I added a DRO and recently replaced the lathe motor with one from a treadmill to give me variable speed on the fly. It was a pretty good unit before these mods and is a very good one now. I also added a windshield wiper motor with a variable speed control to the right end of the leadscrew. This way I can control the speed of the cutter independent to the speed of the spindle, and dial the speed up or down on the fly.

I bought a small CNC mill a few years ago. I think this was literally the last one Little Machine Shop sold of this type; a Sieg KX1. Great little machine.

The last addition was very recent when I decided the lathe part of the 3-in-1 was pretty nice, but swapping between the mill and lathe functions requires a bit of set up time, so a new mill it was. I bought a PM-728VT. Now that is a nice mill!

The first thing I made on the 3-in-1 years ago was a small pin ball valve engine. Looked pretty nice but of course didn’t work. I made a lot of parts for car projects and other things, and then tackled a low temperature stirling engine (the Miser). This was made almost exclusively on the 3-in-1 so it is capable of good precision. And the most surprizing thing was, the engine actually worked the first time I set it up on a cup of hot water! So with that mastered, time to move on to something more challenging….the Little Demon. This has been going on now for a few years but I’ve recently gotten more serious about working on it.

I try and do as much on the CNC as I can, and here is my reason for this. First, I don’t always feel like being in the shop, so working on the computer doing the modelling and programming is still working on the engine without being in the shop. Second, when machining something there is a decent chance of doing something wrong; at least with me there is. By modelling and programming first, I can see what is going to happen before doing the machining. This is important for parts with many holes. A bit more on this later. Also, I still get a kick out of watching the machine do the work.

Please feel free to contribute to this thread if you are making a Little Demon, or any engine with similar parts. Particularly if you have hints and tips that could be useful to others.

I’ll start it off now and give you an idea of what this will be about. Oh, first of all here are the parts I’ve made or partially made so far. Block, carb, air cleaner, distributor, bell housing and adapter, crankshaft, connecting rods, water pump, oil pan, flywheel, rocker covers. Heads are in-work.

Well, this has been a longer intro than I expected, so the more interesting stuff will start with the next posting.

Rick


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## Carbuilder (Jan 2, 2022)

Now that the wordy introduction is done, on to the crankshaft.

I’ve never made a crankshaft like this before and from everything I’ve read, it was going to be a challenge. The issue, as far as I could see, was that the drag of a lathe tool against a fairly flimsy crank can easily lead to it bending, jamming, and being ruined. So how to minimise this?

Here is how I did it. I do have a rotary table for my CNC mill; the 4th axis. But the mill is not huge and there is not room for the 4th axis and a 6” length of material sticking out of it. Here is where things get weird.

My new mill, the PM728 is beside the CNC mill. So I bolted the 4th axis onto the table of the PM mill, but left it plugged into the CNC mill. So I wasn’t using the 4th axis under CNC control, but just using the software to rotate it as needed manually. Here is the setup:




The idea was that I could use the mill to machine away most of the material. I figured a rotating cutter would put a lot less stress on the part compared with cutting it in the lathe. I roughed out the main journals first, as those didn’t require any offset of the crank. So far, so good.




A test cut at the right and then on to the main journals.




I’ve bought a number of kits from Hemingway Kits over the years and highly recommend them. Oh, if you do any threading on the lathe, their retracting tool holder is fantastic! But I digress. I had their Keats Angle Plate kit for a while but never got around to making it. So a time out while I made it. OK, now I’m back. This holder allows for a fairly easy setup for offset turning.







So what I did was to slowly lower the cutter in the mill spindle, while using the 4th axis control to very slowly rotate the crankshaft. I would allow it one complete rotation and then lower it another .010 or so. Of course the surface finish was not good enough for a finished journal, so I left them all oversize to finish on the lathe. This way I only had a few thou to clean up and with slow and careful work didn’t bother with putting any filler pieces between the journals to stiffen it up.

Did it come out perfect? No, but hopefully close enough. Once back on the lathe I cleaned up the main journals to get the runout near zero. I was a bit surprized how flexible it is.




I decided not to push my luck and machine the crank offsets to look more like a real crankshaft. I considered myself a bit lucky to get this far with my first crankshaft.

So that is my multiple mill, semi CNC, rotary table, crankshaft production. Of course a normal rotary table would allow you to do the same thing, just with a lot of cranking. But if machining the crankshaft right from the start on the lathe frightens you, maybe consider this method.

Rick


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## stevehuckss396 (Jan 2, 2022)

Nice work so far. I will be following this one close. That little demon v8 is one of my favorite engines.


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## Carbuilder (Jan 2, 2022)

Thank you Steve. And thank you very much for designing this amazing little engine and providing support when we need it.

While I'm here, how about a small repair I made. Those with good eyes no doubt noticed the picture of all the engine parts that shows the timing cover with a strange piece sticking out of it. 




I machined this part on the CNC. With parts like this I leave small tabs (to keep the part from coming loose) and cut about .020" below the material thickness between the tabs. So I started this one going and then remembered I forgot to put a scrap piece under it; the cutter is going to go right through and into the table otherwise. So I stopped it, added 1/16" aluminum scrap under it and started it again. But I forgot to re-zero the upper surface of the material, so the cutter went .062" too deep. I stopped it when I realized, but the one hole that wasn't supposed to go right through, did.

I took a small piece of scrap I had, turned it to fit about .040" into the part, and pressed it in with some locktite. 




Cut it off, machined it almost flush, and another part saved. I also put an extra hole in it for some reason; I blame the CNC for that one. I plugged that with a small countersunk screw (not shown here).




So don't think you have scrapped a part without giving some thought as to possibly fixing it. 

Rick


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## rrocky (Jan 3, 2022)

Carbuilder said:


> This will be sort of a build log, but hopefully with a difference.
> 
> Here is what I am hoping this thread will provide. This will not be a normal build thread with many pictures of my finished parts. This will be more of a show and tell as to how I made the parts; how they were set up in the machine and how I made them that may be different from how others did it. And most important, I’ll show the mistakes I made on some of the parts and how I repaired them without having to machine a new part.
> 
> ...


Hullo, would you share the gcode for these parts I am making one also have put up some pics on here somewhere Cheers Peter


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## xpylonracer (Jan 4, 2022)

Hi Rick

Please advise which material code did you use for the crankshaft and what is the diameter of the main and  offset journals ? 

xpylonracer


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## Carbuilder (Jan 4, 2022)

I followed the plans and used 1144 steel for the crank. The main journals are .373 dia and the offset ones are .248 dia. The diameters are from the plans; mine are not exactly that, but I adjusted the bearing sizes to match what I ended up with.


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## xpylonracer (Jan 4, 2022)

Hi Rick
Thanks for the info.

xpylonracer


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## Carbuilder (Jan 5, 2022)

Here's another one along the lines of not wasting material.

I thought the bell housing would be a cool piece to make with that nice curved profile. I needed a piece of aluminum 2.5" diameter. I had lots of 2.25" and lots of 6". Obviously one was too small and I really didn't feel like taking half a day to turn a 6" chunk into 2.5" with mountain of swarf. Kept looking and found this piece.




I got this from work some time ago when they were cleaning out a lab. It's aluminum, but not sure what type. BUT...it obviously had a large hole in it. Since the rear of the bell housing is not structural, I used this piece, machined the hole to an accurate diameter (around 1" since it was almost there), pressed in a smaller piece, and finished machining it. I was thrilled how it came out. Almost Clickspring precision!







If it wasn't for the different colors on the outside at the seam it would be pretty much invisible. 

So a little bit of thinking outside the box when choosing raw material to use on a project can save time and find a use for that piece you picked up a while ago and couldn't really see a use for.

Rick


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## michael-au (Jan 5, 2022)

Carbuilder said:


> I followed the plans and used 1144 steel for the crank. The main journals are .373 dia and the offset ones are .248 dia. The diameters are from the plans; mine are not exactly that, but I adjusted the bearing sizes to match what I ended up with.



Rick
Did you find a supplier in Australia for the 1144 steel

Michael


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## Carbuilder (Jan 5, 2022)

Since I'm in Canada, I didn't look for a supplier in Australia.  

I see that I didn't have my location identified. I'll correct that.


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## michael-au (Jan 5, 2022)

Carbuilder said:


> Since I'm in Canada, I didn't look for a supplier in Australia.
> 
> I see that I didn't have my location identified. I'll correct that.



Sorry I mixed you up with another person. :-(
Michael


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## rrocky (Jan 5, 2022)

michael-au said:


> Sorry I mixed you up with another person. :-(
> Michael





michael-au said:


> Sorry I mixed you up with another person. :-(
> Michael


Edcon steel in AU


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## Carbuilder (Jan 13, 2022)

Making split journal bearings.

I've read about the method of soldering 2 halves of brass together, then machining the bearing. I thought I would try it without soldering, since it looked like the ER collet I use would hold the material just fine. Well, it does.







But, it does waste a fair bit of material since you need a certain length to hold in the collet. So I tried the solder method and figured the best way was to also solder it onto the end of a longer bar for machining.




This worked well, but there is the layer of solder to deal with, even though I clamped the parts together for soldering. So when it was done and I de-soldered them and ran the mating surfaces over some very fine wet/dry paper to smooth out the remaining solder, the ID was just a bit under what I machined. I "massaged" it a bit to get it to fit. So both methods worked, but I would not say they were ideal. 

I'm thinking that since the crank is supported on both end by ball bearings the journal bearings are to account for any deflection in the crank. I probably have a bit more clearance than I should in those bearings, but hopefully it will be OK.

Rick


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## Carbuilder (Jan 15, 2022)

I managed to ruin a few heads by not reading the drawings properly. Steve straitened me out. I thought the ruined heads would not really be good for anything since they were so full of holes, so not much usable material left. But...

My angle vice takes up a fair bit of vertical room, so if I put that in the small CNC mill it doesn't give much Z axis clearance. The normal small machinists vice fits much better, but of course doesn't hold parts on angles....or does it...

I took 2 of the ruined heads and milled a groove in each at an 18 degree angle and that works perfectly to hold the heads for milling the rocker cover area.




I do a lot of engraving on the CNC mill (making custom car badges and stuff like that) and some of the cutters I use work very well for spot drilling for small holes. This type not only works great for engraving, but also for spot drilling the many, many holes in the heads. This is 1/8" diameter shank, 60 degree point.




I did finally get a pair of heads done. Only have to drill the intake and exhaust ports and they will be finished.







Starting on the intake manifold now.

Rick


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## michael-au (Jan 16, 2022)

Carbuilder said:


> I managed to ruin a few heads by not reading the drawings properly. Steve straitened me out. I thought the ruined heads would not really be good for anything since they were so full of holes, so not much usable material left. But...
> 
> My angle vice takes up a fair bit of vertical room, so if I put that in the small CNC mill it doesn't give much Z axis clearance. The normal small machinists vice fits much better, but of course doesn't hold parts on angles....or does it...
> 
> ...


Nice work on the heads


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## Carbuilder (Jan 22, 2022)

I made the intake manifold. It certainly looks complex from the drawings. I found that I had 3D modelled it in Fusion360 some time ago...forgot about that. So having that model I decided to CNC the upper surfaces of it.

I added rounded corners to the outside of the runners to give it a bit of a cast look. Most of my CNC work I do with VCarve. I also have Desk Proto which I haven't used much, but decided to give it a try here. I machined the blank with the angled sides before deciding to CNC the rest of it.

I used 2 future holes in it to secure it to a waste piece of aluminum. The holes are counterbored for screws that thread into the waste piece. The holes are undersized from what they will be in the finished intake, so it's not like they are something I have to fill later.




I used an 1/8" flat end mill for the rough passes, and then an 1/8" ball nose end mill for the finish ones. I took slow cuts with a fair bit of overlap, so it took a long time. Really pleased with how it came out.




I still have to go back to the heads and finish the drilling of the intake and exhaust ports.

Rick


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## michael-au (Jan 23, 2022)

Good workmanship  on the intake, doesn’t look like an easy piece to make


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## bob shutt (Jan 23, 2022)

I sand blasted mine to give it a casting look.


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## Carbuilder (Jan 23, 2022)

I've got one of those cheap little all-in-one sand blasters but never tried it. A friend with one said it works very well. I really have to try it one of these days.


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## Carbuilder (Jan 24, 2022)

Time to make some really tiny parts. But first, how to part them off without losing too much material. I don't want to make a part that is only .052" thick and then remove more than that parting it off. So...

I took a piece of broken bandsaw blade, .025" wide, and cut/ground it to fit in the parting tool holder. Made a tapered piece of aluminum to clamp the blade in place. It is a bit flexible, but only needs about 1/4" protruding.





To make the spring retainers I started with 1/4" rod and brought it to the correct diameter for about 1". Drilled it as required to the same depth.




Used a 3/16" end mill to produce the counterbore in it, .020" deep.




Then used my little parting off tool to produce the groove in the backside, .030" in from the end and about .125" dia. The parting tool worked great. I didn't slow the lathe down much from normal machining speed for this material/diameter.




Zero'd the dial and then moved it .022" to the left and parted it off. Before the parting was done I cleaned up the edges with a small file to minimize the hand work after.




Then just clean up the end that is still in the collet and repeat. The cut-off part needed a little cleaning up since even with very light cuts with a sharp cutter the inner hole does tend to close up a bit from the material rounding in from parting. But doesn't take much to clean up, other than trying not to drop it or file my fingers.

It is difficult, for me anyways, to get a decent picture of tiny parts like this.




Rick


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## Arild (Jan 25, 2022)

Do you know if anyone tried to cast all the aluminium parts for this engine?


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## Carbuilder (Jan 25, 2022)

Not as far as I know. Not sure how much of an advantage it would be with so much machining needed on each part. maybe someone that does home casting will comment.


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## Carbuilder (Jan 30, 2022)

On to the rockers.

I probably spent more time trying to figure out the best way to make these than with any other part. They have to be machined from 2 sides and are very small and difficult to hold. So here is what I did.

CNC machined them in a block of material a little thicker than required. I didn't want to machine them with tabs holding them in place like I usually do, since they are so small.




Then, borrowing an idea from another thread, I put epoxy in the machining. I didn't want to waste too much epoxy, so didn't fill it up all the way, just enough to hold the parts as I machined from the back side.




Then flipped it over and machined to final thickness:




I popped the parts out and pulled off the epoxy. Then marked the parts for the threaded holes. There are 8 right hand and 8 left hand...plus a spare or 2.




Drilled and threaded, and a fixture plate drilled. The idea is to put the rockers on the fixture, attaching with the threaded holes in the rockers through clearance holes in the fixture with screws from the bottom.




With the rockers screwed onto the plate, aligned with a square as each was tightened down, the small holes are drilled from the underside of the fixture plate through the rockers. This hole is used to put a 1/16" pin through each rocker to keep it from rotating. The hole will be in the middle of the rocker slot, so will be removed later.




Pins installed and rockers machined again.




So now I have a bunch of semi-finished rockers.




My concern at this point is the strength of them....or lack of it. I know they must work, but some areas are pretty thin. The slot still has to be machined where the small holes are. That slot leaves .020" material thickness between the slot and the oval hole. .020" thick aluminum can't have much strength. Then there is the spring retainer counterbore that has to be put in the same area, further reducing the material.

To be a bit clearer, this is the material that is removed when slotted:




I'm wondering about cutting the retaining groove in the valve a little lower (.020"?) and maybe making the valve stem a little taller (another .020"?), that will drop the spring retainer .040" further from the bottom the rocker, thus avoiding the need to machine the spring retainer clearance in the rockers (maybe). Yes, that will change the valve geometry a little, but enough to matter?

Not sure yet how I'm going to machine the slot. Bandsaw it in and then cleanup with a file? Not sure I like that. Come up with a fixture and machine with a 1/16" end mill with the rocker held vertical?

Rick


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## michael-au (Feb 2, 2022)

good work on the rockers
looks like the epoxy idea works good


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## Carbuilder (Feb 3, 2022)

michael-au said:


> good work on the rockers
> looks like the epoxy idea works good



Yes, something to keep in mind that may come in handy. I used a clear JB Weld that I had. It didn't seem to cure really hard (could have been me not mixing the proportions perfectly), but that may have been an advantage. It held the parts in place fine, but also pulled off fairly cleanly without using heat.


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## Carbuilder (Feb 3, 2022)

Repairing a camshaft.

I've roughed out the cam for the Little Demon. My plan is to CNC it, but I first machined the ends down to the rough final diameter and cut the spaces between the lobes. I did mess up one space between lobe groups that resulted in one lobe being undersize in width, .10" as opposed to .155". The others aren't all perfect, but are a lot closer.




It would probably work fine as-is, but it bugs me. So I thought I would repair that lobe. The first plan was to machine a thin piece and silver braze it in place. I was a little concerned with distorting it, but that may not have been a valid concern since it would all be machined afterwards. But JB Weld is generally regarded as being able to glue engine blocks back together (I actually did use it once to glue a piece of a 5L engine block back on after I cut it off and then wanted it back on). So, epoxy it is.

I machined a piece of the same steel a little thicker than I needed. Of course I had to make 2 pieces and then cut them to get this:




JB Welded in place:




Cleaned up on the lathe after curing:




Really pleased with how it came out.

Rick


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## michael-au (Feb 3, 2022)

Nice job on fixing the came, save a lot of time and material


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## Carbuilder (Feb 3, 2022)

I'm kind of nervous about putting this on the CNC mill and pressing the start button. Really don't want to see it messed up, so I'm trying to sort out some other issues with the programming first. I'm close to pushing the button though!


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## michael-au (Feb 4, 2022)

I can understand the nervousnes

looks like I have to get a new controller for my mill, giving me problems with the Y axis, from what I have read there is a lot of people that have hade the same problem,
Im leaning towards the Masso controller and doing away with the computer


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## rrocky (Feb 4, 2022)




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## raveney (Feb 5, 2022)

Arild said:


> Do you know if anyone tried to cast all the aluminium parts for this engine?


Lost Foam cast an aluminum tunnel ram. Thread here








						Miniature Tunnel Ram Intake
					

Attempting to cast a 2" high, 5" long aluminum tunnel ram for a model engine I've been working on. This is a first time evolution for lost foam...




					forums.thehomefoundry.org


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## stevehuckss396 (Feb 5, 2022)

Cool thread but you have to be a registered member to blow up the photos big enough to see anything.


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## Carbuilder (Feb 5, 2022)

Didn’t know that. I’ve been putting them as thumbnails so they would be in the text. I just logged out and had a look and could see them all fine. Should I be doing something different with the pictures?


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## stevehuckss396 (Feb 5, 2022)

Your pictures are fine! I was refering to the photos in the miniature tunnel ram thread I can see them but they are tiny and I cant blow them up as an unregistered guest.

Your thread is great. Don't change anything. I'm reliving my youth looking at it. I't been 10 years.


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## Carbuilder (Feb 5, 2022)

When I log out on my iPad or desktop Mac, I can see and enlarge them fine. Does it somehow know I am still a member? Don't know what else to do with them unless someone advises me.


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## Carbuilder (Feb 5, 2022)

stevehuckss396 said:


> Your pictures are fine!



Oh, OK. Good.


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## Carbuilder (Feb 10, 2022)

Quick way to get the camshaft blank ready.

When I made my first camshaft blank (which I ruined when machining the lobes), it took quite a while to machine the grooves that are between each lobe. I used a parting blade that I ground thinner.




I used a collet chuck and extended the blank out as the grooves were cut (cutter looks like it has more taper than it actually did).




This took quite a while, broke off the end of the cutter once, and was not a fun operation.

I've gone through a number of test pieces in sorting out an issue I had with mach3, but kept thinking of how to speed up that process.

The first thing I did was blue the whole length, put a scribe in the tool holder, and use the DRO to move it to each lobe position. You could certainly do this without the DRO.




Now, how to cut all those .0535" wide grooves? Would you believe I went from the above picture to this in about 4 minutes?




You would? They still need to be cleaned up a bit, but that should be a lot easier, faster, and less clenching than using a parting tool right from the start. So how did I do it? With this:




The grinding blade in that tool is .040" wide. I just held it by hand and visually lined up the blade with the marks. I ran the lathe slowly backwards, the blade forwards, and it cut nicely and quickly. That is my favourite tool for cutting off small bolts, music wire, fibreglass panels, hardened stuff....super handy.

The grooves are more or less a bit under the final width required (I was just holding the tool by hand, so ended up with grooves closer to .050" wide). I'll grind a parting blade to about .053" wide and use it to clean them up and take them to the correct depth.

I was really pleased/amazed that it worked so well.

Rick


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## michael-au (Feb 11, 2022)

learn something new every day


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## Gabe J DiMarino (Feb 11, 2022)

After cutting the lobes in the wrong place on my first cam I blanked out a second in 1.5 hours .Cam material is 420 stainless cut it with a high speed tool bit ground to .050 thick .


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## Carbuilder (Feb 11, 2022)

Yes, I cut 2 cam lobes a bit too thin on my first one. I think a key point here is to blue and mark all the cuts first, so you can see that they all look correct before cutting.


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## Carbuilder (Feb 19, 2022)

Finally, I have a camshaft!

I know I could have produced the cam in a fraction of the time it took me if I made it in the traditional way; indexing it around on the lathe and taking cuts every 5 degrees or so. But I was determined to do it on the 4th axis of the CNC. And after many weeks of trials, incorrect software settings, and broken cutters, it is done. It was cut with a carbide 3/32" 4 flute ball nose cutter, with very conservative speeds (after breaking too many cutters). Thus, 6 1/2 hours of CNC.





After the lobes were CNC'd, I did mess up the end that the gear goes on. Got it just a bit undersized. So I machined it down to about 1/8" diameter and made a thin steel tube to press/locktite on. Then machined it to the proper dimensions.




One interesting thing I found (that turned out to help me a lot) is that with the spacing of the lobes at that end of the cam it grips in the 1/2" collet perfectly centred, as you can see in the picture.

My wife says she never wants to hear the word camshaft as long as she lives.....or maybe just as long as I live?

Rick


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## stevehuckss396 (Feb 20, 2022)

Nice work. Did you capture any video of the machine running?


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## Carbuilder (Feb 20, 2022)

Thank you Steve. No, I didn't video any of that one. I did take some video early on when trying to see what the issue was with my CNC. That is when I saw the cam stop rotating but the program kept running, along with the 4th axis indication changing (when it wasn't actually moving). So video of the final machining would have been pretty boring since it was very slow.

I machined it with what DeskProto refers to as "around A-axis" machining. The cam rotates and the cutter moves up and down, centred on the axis of the cam. Then it moves over on the X-axis and repeats. It does it with a rough pass and then a finish one. Over, and over, and over............


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## Eccentric (Feb 20, 2022)

Congratulations on finishing your Camshaft.  I know the process of getting the CNC working with the 4th axis was a real challenge, but next time will be a breeze.  You must really feel satisfied to have worked out all the kinks in the process and have a nice camshaft to show for it.  Great job.


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## Carbuilder (Apr 14, 2022)

Got back into the engine project. Some of the delay was buying a Taig CNC lathe. Found a used, but not used (person bought it but never actually used it), one and it took time to set it up and learn how to program it; different than a CNC mill. The first items were the lifters for the engine. After a LOT of trials, learning, mistakes, finally made some nice parts.

Working on the valves now.

I put together a video on making the lifters.

Rick


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## michael-au (Apr 14, 2022)

Very good Rick
Good find on the lathe, works great, nice looking parts
You will be finished in no time 

Some of my delay is setting up the mill with a new controller, slowly getting there

New parts are inside the line


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## Carbuilder (Apr 16, 2022)

Don't know about being finished in no time. If I would spend less time on the CNC stuff and just make parts then maybe.  

I'm finding a lot of inconsistencies with trying to get the dimensions correct on the parts. Once it is done and ready to go I can make one after the other with almost dead-on precision. But I run a trial piece, measure it, tweak the program or setup, make another one, and maybe it changes the way I intended and maybe not. It has to be something with mach3. I've briefly looked into Masso and Centroid Acorn as alternatives. I'm used to mach3 on my CNC mills, but on the lathe it seems to be a whole different story.

Trying to get that little slot at the end of the valve the correct depth is driving me crazy. According to a simulator it should be cutting the part almost in 2. But when I run it, it barely cuts into the part. Very strange.

Hope everything works out with the new controller for you. We'll get there eventually!

Rick


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## michael-au (Apr 16, 2022)

I have the valve partly done, need to finish them off with wet and dry sand paper so the are nice and smooth
I am going to make a piece of round aluminium with a hole the valves fit through and then cut a slot down the side so it can be clamped in the lathe chuck, then I will turn the groves on the end

Valve looks good though, I found there is a big difference programming the lathe over the mill too


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## bob shutt (Apr 17, 2022)

Not sure how far you are turning back to put groove in. I only turn far enough to clear groove tool leaving as much strength as you can. Then come back in with turn tool.


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## Carbuilder (Apr 17, 2022)

Yes, that is how I'm doing it. I turn it down to .098" dia for a short length, cut the groove, then come back and turn it to .094" dia up to the point in the stem where the diameter changes. So it isn't a deflection issue with the groove. It must be something wrong I'm doing. I did get the groove close to the correct depth a couple times, but then tweaked things a bit to get it correct and sometimes it works and sometimes works the opposite. 

I'm using EziLathe to generate the code, which is a pretty cool program. When I run the code in that simulator the groove almost cuts the part in half. In reality it doesn't cut deep enough. So that is the strange part. The tool setup is correct on the machine. Something strange I'm finding is that if I stop the machining before it is complete (like if I see that something is not right and don't want to complete the test part) and return tool #1 to 0,0 it isn't the 0,0 that it started out at. So something is changing the 0,0 point and that is throwing things off. But not if the machining completes. A setting in mach3 that is wrong? I should probably ask on the mach support forum and post my code. 

I don't have issues with mach3 on my CNC mill or router. If something is not machining correctly I can usually find what I did wrong. But the mach3 turn seems to be a whole different story. After doing some searching around on the net it does seem like most people agree with this. I'm always up for learning new things so thought it might be interesting to dump mach3 on the lathe and get something else. Why not start a whole new system with its frustrations?   

Rick


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## mayhugh1 (Apr 17, 2022)

Carbuilder said:


> Yes, that is how I'm doing it. I turn it down to .098" dia for a short length, cut the groove, then come back and turn it to .094" dia up to the point in the stem where the diameter changes. So it isn't a deflection issue with the groove. It must be something wrong I'm doing. I did get the groove close to the correct depth a couple times, but then tweaked things a bit to get it correct and sometimes it works and sometimes works the opposite.
> 
> I'm using EziLathe to generate the code, which is a pretty cool program. When I run the code in that simulator the groove almost cuts the part in half. In reality it doesn't cut deep enough. So that is the strange part. The tool setup is correct on the machine. Something strange I'm finding is that if I stop the machining before it is complete (like if I see that something is not right and don't want to complete the test part) and return tool #1 to 0,0 it isn't the 0,0 that it started out at. So something is changing the 0,0 point and that is throwing things off. But not if the machining completes. A setting in mach3 that is wrong? I should probably ask on the mach support forum and post my code.
> 
> ...


One or two things to check for with lathe CNC: 1) make sure that both you and your software(s) are using the same definition for depth-of-cut, i.e. radius or diameter, and 2) make sure that both you (during zeroing) and your software(s) are using the same definition for tip of tool. 

I ran into both the above when using mach3 with my CAM software when I first started. I still have issues when trying to do precise profiling. I'm not sure my CAM software accurately handles the tip profile of some of the cutters I use. - Terry


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## xpylonracer (Apr 18, 2022)

Rick

Check to make sure you haven't got a backlash problem on the X axis as that could cause loss of travel into the work after a toolchange if the
grooving tool moved out from the job to provide clearance before making the groove cut.

xpylonracer


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## Carbuilder (Apr 18, 2022)

I'll double check for backlash, but pretty sure there is basically none. The grooving cutter moves into position and then slowly makes the cut. But the depth of it is not consistent with what I've programmed. The other dimensions are generally good. But like I said, sometimes when I return to tool #1 and zero it, it isn't where it started; maybe .050-.100" off on the X-axis. 

The radius/diameter thing seems to be good since the part is being machined to the correct size, other than the groove. I'll post a bit of the code in case anyone is curious. I am slowly learning the different codes, what they mean and what they do. The reason for flood coolant being turned on instead of the spindle is that the spindle outlet on the control box didn't seem to work, but the coolant does. Since I'm not using coolant I plugged the spindle into that outlet and use it to power the spindle. It starts with this:

(EziLathe Version 1.7.3.0 Mach3  2022-04-09 12:58:59 PM)
(Dxf file = Valvex  Bar = 0.25)
G18 G40 G49
G90 G94 G80
G20 (Inch)

T0101 ( tool cuts with left side)
(Process = O.D. Turning - Cut Right to Left)
M08  (Flood Coolant On)
G00 X0.35 Z0.05
(Rough #1 R-L)
G00 X0.245
G01 Z-0.1754 F5.0
G01 X0.35
(Rough #2 R-L)....

that goes on a bit and machines the end of the blank where the groove will go. Then the groove cuts:

T0303 (slot .028 wide)
G00 X.100
G00 Z0.1
G00 Z-0.08
G01 X0.01 F0.25
G00 X0.105
G00 Z.1

See how this should be cutting the part almost in 2 (X0.01)? It doesn't come close to that depth.

Something wrong with the initial codes at the start?

Rick


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## bob shutt (Apr 18, 2022)

Call up the offset for the tool on the rapid line 
T0100
GO X 0.300 Z0.050 T0101

T0300
GO X0.100 Z0.100 T0303

Sometimes lathes do not want to pick up right unless it is moving.


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