Werowance attempts Upshur Vertical Single

[werowance]

gears go round and round now on the correct shafts this time.....

 

[werowance]

now i was looking at the rocker arms and have the material down to .125 but looking at the tip of the rocker arm in the drawing it doesnt give any type of radius or anything. i guess just file or sand it till it looks nice?

 

[Brian Rupnow]

Glad to see that you are still in the game. I know just how discouraging it can be when halfway thru a build you find that something has gone awry. Keep on truckin' Werowance.--As the rocker arm rocks, it does actually swing in an arc on top of the tappet and on top of the valve. You need the adjustment as shown on one end so you can set the valve lash. The other end should be formed with an arc as shown, but it's not critical.-Brian

 

[Art K]

I would echo what Brian said, that it wasn't critical. The arc is just so the tip of the rocker follows the valve.
Art

 

[werowance]

starting to look like an engine. just got the slot done for the gear clearance and then mocked things up. the tappet guids are just barely inserted is why they are crooked

 

[Brian Rupnow]

Looking very good. I am following your progress with interest.---Brian

 

[werowance]

Got a start on the gear cover. took a piece of scrap brass cutoff about 3/4 inch long and bored it to size and cut the outside to size. then parted it off. I will take a piece of square brass tube to make the sides / flanges. plans say to glue it on but I hope I can fit some 2-56 screws on the flanges. if not ill cut the flanges off and just glue it on like it says. sides will be soft soldered to the final half moon shape.
I also got some stock cut close to size and locktighted together so I can cut both rocker arms at the same time. left it to cure and went in for dinner.

 

[werowance]

i don't think I'm going to be able to attach it with 2-56 screws. this is as far as I got last night. just roughed in on the flanges to see how much room I would have. hope to get the flanges squared up and closer to size tonight. maybe I can get a 2-56. if not ill just epoxy it down like the plans say to do

 

[werowance]

could not do the 2-56 screw idea so fell back to what the plans say. I trimmed the tabs mostly off the sides. left a little bit for the glue to adhear to. also had to cut a little relief out so the screw holding the aluminum plate down would clear. then cleaned it all up. on the note of cleaning up. is there a common on the shop shelf cleaner that will remove dikem? don't like running in the house with dirty hands getting the wifes acetone fingernail polish remover. she probably doesn't like me doing that either lol. I guess I could just buy a bottle for the shelf but was just curious of there were other common things that will bring it off.

and I saw Brian R say on one of his threads yesterday that he likes to make at least 1 part a day....im lucky to get a part done a week this simple part has been almost a week.

 

[Sprocket]

I think plain acetone is the usual solvent. Two universal (almost) solvents, acetone and water. Besides, there is other stuff in nail polish remover you might not want to have on your surface.
Acetone will de-fat your skin, can be absorbed through the skin, other health risks, but a really good straight solvent and degreaser.

 

[Ghosty]

werowance,
This is what I use, works well, go's by different names in other country's., hope this helps.

Cheers
Andrew

 

[Brian Rupnow]

Go to your nearest hardware store and buy laquer thinner. It removes dykem easily.

 

[CFLBob]

I was going to suggest denatured alcohol, which is what I've used. That's called methylated spirits in other places.

 

[werowance]

denatured Alcohol, now that's something I have a big jug of in the garage. bought it to run the flame eater with which doesn't use very much. and only about 7.00 us for a gallon of the stuff.

I also have some laquer thinner as well in the garage. rarely get it down because I don't do much painting.

thank you all for those suggestions.

so for todays question.... or at least the first question of the day I have been studying about cam making and over the years have watched / read many tutorials from many different sources. I'm leaning toward the rotary table on the mill method but I just still don't understand how to arrive at the correct measurements to obtain the egg shape of a cam. I realize its just move a tad, rotate a tad and then cut but how much to move and where to start the cut etc - how to calculate the measurements of each move?

do any of you know of a good post or tutorial I could read or watch that might explain the method a little bit better? something that shows how they figured out how much to move the part in before the first cut? seems each cut is rotated about 1 deg before the next cut and once all done finished with a file or sand paper.

 

[L98fiero]

Go to your nearest hardware store and buy laquer thinner. It removes dykem easily.

Brian, lacquer thinner is a nasty solvent, it's very flammable, the toluene component has a flash point of 0°F and a lower flame limit of just 1.2%, pretty comparable to gasoline and the Methyl Hydrate/methylene/methyl alcohol/wood alcohol component breaks down into formaldehyde when absorbed through the skin. Acetone/dimethyl ketone/propanone absorbs through skin easily too and while it can be toxic, it is produced and disposed of in the human body through normal metabolic processes.
The other thing to consider is that your new TIG welder might not like the possible additives in the lacquer thinner when you clean the parts to be welded while acetone is the 'cleaner of choice' for many years, and it removed layout dye, too!

 

[awake]

Weworance, are you looking to make cams with flat flanks or rounded flanks?

I have vast experience in this area, having cut a grand total of two - count 'em, two! - cams. Actually only needed one, since the intake valve is atmospheric, but I cut these as part of a gear, and it turns out, to my great surprise, that a 40-tooth gear does not work when the plans were based on a 48-tooth gear.

Ignorance usually stops me from offering an opinion, but since I have been thinking about this recently, I'll throw in my $0.02 and then sit back, waiting for someone who actually knows what he/she is doing to correct me!

For a straight flank cam, which is what I recently cut (twice), it is quite simple. Turn the cam blank to the maximum outer diameter. Set up the rotary table so that the cam blank is centered on the table and the table is centered under the spindle. Move the Y-axis so that the cutter clears the cam blank. With the rotary table locked at 0° (or whatever setting you want to start at), start making passes along X to cut the flank, moving in the Y-axis to take however deep a cut you feel comfortable taking each time, until you reach the radius of the base circle of the cam (where the cam is not activating the valve).

At this point, lock the Y-axis. Index the table however many degrees you want to do at a time, and make another pass. Index the table again, make another pass. Continue until you have indexed the table through the appropriate number of degrees. Since the shape has been generated by a series of straight cuts, the curve will consist of tiny facets; lightly file to smooth these out. File to round over the points where the straight flanks meet the maximum outer diameter.

Note that I have described this with the cuts happening along the X-axis, but there is no reason it can't be done with the cuts on the Y-axis instead (swap X and Y above). It can also be done with the rotary table in the vertical position (or even using a spin indexer), adjusting the Z-axis to get to the base circle.

For a rounded flank cam, there are two options. One is to do the same procedure as above, except that you will need to calculate the Y-axis settings for each index of the rotary table to give you the rounded flank - rather a pain, and more likely to succeed if you have DROs on your mill. This approach does allow using the rotary table in either horizontal or vertical positions, as suggested in the previous paragraph.

Option 2, which will only work with the rotary table set horizontally, is to set a boring head up to cut an outside diameter, either by turning a standard boring bit 180° to face inwards rather than outwards (this requires running the boring head backwards, which further requires that the boring head will not unscrew itself in the process), or by making up an inverse boring bit. Set the boring head up to cut the radius called for on the flanks of the cam. Set up the rotary table and the cam blank as above, and lock the Y-axis on 0 (i.e., centered on the rotary table). Move the X-axis to 0 as well. Lower the boring head and check to be sure the boring bit will clear all around the cam. Move the X-axis slowly until the bit just contacts the cam blank. Note the setting on your DRO (or re-zero it). Now you will take a series of boring cuts (e.g., using the auto-feed if you have it, or a fine feed, or so on), moving the X-axis each time to take the depth of cut you are comfortable taking each time, until you have moved the X-axis the distance between the radius of the flanks and the radius of the base circle. This is now one flank. Begin indexing the table however many degrees you want to do each time, making a boring pass, until you have indexed around through the appropriate number of degrees. The final pass establishes the other flank. Once again you will need to smooth out any small facets with light filing, plus you will need to round over the nose.

Okay, let the corrections begin ... those of you who actually know what you are doing, did I get close? Completely wrong? Somewhere in-between?

 

[werowance]

wow, that's a whole lot of info and not sure I understand it all but ill say this.
I believe I need option 2 for this engine as it has tappets. the Webster was easy and I used option 1 method for that cam with flat flanks.

option 2that you describe I believe is the one that I saw Chuck Fellows do a post on with video. which I never could understand. when I get home and can get my hands on the mill and eyes on these instructions it may make better sense to me
here is a picture of the cams I need to make, Mr. Upshur used a method on the lathe which used an offset arbor to do it and that's another method I have seen and also still don't understand lol. but I figure rotary table / mill method would be easier since no need to make the arbor or holding tool or fixture whatever you want to call it thingy majig

 

[werowance]

ok in option 2 you say to "Set the boring head up to cut the radius called for on the flanks of the cam" a lot of plans I see do not specify a radius for the flanks, but just the tip and the base circle only.

here is the written description in the plans for making the cam using the fixture. and I don't see how I can calculate the flank radius using it? I'm sure there is some math that I could use to calculate the flank radius by taking the blank diameter, the final cam base circle and then tip radius but I don't know how I would do that math or what the formula would be. I failed 2 years worth of pre-algebra in high school but if I know what the formula is then I can certainly do the math using the formula. I think I will spend some time looking to see if there is a formula for it out there somewhere online

 

[werowance]

ok, im borrowing this image from Brian Rupnows thread - https://www.homemodelenginemachinist.com/threads/quick-way-to-cut-a-cam.26315/#post-288291

and it makes sense on the setup that you (Awake) described in option 2. but how to get that flank radius circle that i need is what puzzles me most now

 

[awake]

As it happens, I just read the chapter in Malcom Stride's book, Miniature Internal Combustion Engines, on cams. He suggests that the rule of thumb for the flank radius is 2 times the base circle radius - but also indicates that this is a parameter that can be experimented with to adjust the acceleration of the valve as it opens/closes.