You have lost me.... How does this thing work?
Not seeing any mill boring tools for 7/8" or there abouts etc????
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Failed Shim Punch Project
- Thread starter YYCHM
- Start date
You have lost me.... How does this thing work?
Not seeing any mill boring tools for 7/8" or there abouts etc????
OK.... down to 1/2". Where?
That explained it. I thought the tool was mounted on the side of the head, thus my confusions as to how one could stuff the head in such a small hole.
Thanks!!!
I think what I'll do is pickup a boring head and try boring the OD hole on the die I have and turn a matching punch to see if that improves the situation.
When it comes to boring heads I see designations such as 2", 3" etc. What does the 2", 3" represent?
When it comes to boring head tooling I see designations 3/8", 5/8" etc. What do these measurements represent?
Thanks,
When it comes to boring heads I see designations such as 2", 3" etc. What does the 2", 3" represent?
When it comes to boring head tooling I see designations 3/8", 5/8" etc. What do these measurements represent?
Thanks,
2" & 3" is the nominal OD of the head itself
3/8" & 1/2" is the shank diameter of tools that insert into head via the holes you see. They are standardized, kind of similar to IMP end mill holders.
Larger heads have longer throws so extending the radius you can bore bigger holes. But they also are heavier & more expensive. BH sizing is more about the mill you have, the power, intended work & available headroom. Don't underestimate headroom on a smallish mill. By the time you insert a boring head, have a tool sticking out the bottom (even a stubby) vs the work piece + vise.. it can gobble up vertical height pretty quick. Get some measurements off the net & mock this up before you commit the $$.
3/8" & 1/2" is the shank diameter of tools that insert into head via the holes you see. They are standardized, kind of similar to IMP end mill holders.
Larger heads have longer throws so extending the radius you can bore bigger holes. But they also are heavier & more expensive. BH sizing is more about the mill you have, the power, intended work & available headroom. Don't underestimate headroom on a smallish mill. By the time you insert a boring head, have a tool sticking out the bottom (even a stubby) vs the work piece + vise.. it can gobble up vertical height pretty quick. Get some measurements off the net & mock this up before you commit the $$.
Boring the die hole ID to match the punch OD appears to have done the trick.
I picked up a 2" boring head and a set of 3/8" boring bars today.
After cleaning up the OD punch on my lathe, I proceeded to bore the die OD hole to just fit the punch.
This worked way better than what I did before which to try to turn the punch to match the die.
The OD punch and die is now cutting the shim ODs nice and clean and round. The ID punch and die now need the same treatment as they are tearing the shim ID more often than not. Still better than what was occurring before.
Getting closer. OD looks good, ID not so much.
Note that I also pinned the die plates in two places.
I picked up a 2" boring head and a set of 3/8" boring bars today.
After cleaning up the OD punch on my lathe, I proceeded to bore the die OD hole to just fit the punch.
This worked way better than what I did before which to try to turn the punch to match the die.
The OD punch and die is now cutting the shim ODs nice and clean and round. The ID punch and die now need the same treatment as they are tearing the shim ID more often than not. Still better than what was occurring before.
Getting closer. OD looks good, ID not so much.
Note that I also pinned the die plates in two places.
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Bofobo
M,Mizera(BOFOBO)
Your punch should be shaped like this, i used/built a shop made, item specific pneumatic punch ( making shim reinforced rubber valves for a classified project) case hard is a good idea, and a guide block matched to the punch plate for the close tollerances required for repeatability.
Attachments
I'm not sure that this has come up but you will need to grind the od of the punch tool with back relief and the face with a concave(I think I've got it right, center needs to be back from the rim) as well. Then you pretty much have to do the inverse to the plate that it mates with. The idea is that you get a shearing action at the faces but it doesn't have to fight to keep going, once you have the cut completed there needs to be a little room for the punch in the die. Look at rotary broaching for the general idea on relief on the punch tool. There's a lot of information on this subject out there. If I remember right stefan gotteswinter has done this exact thing and I'd doubt anyone on this forum has a better background and can explain or make this tool as well..
historicalarms
Ultra Member
Just an observation here after a re-look at the photo's with a suggestion . I noticed your hold-down bolts are all on one side...would this not pinch one side of your shim stock in your form and tilt the forming base off the shim stock on the other side of the hole causing a tear instead of a cut after the center I.D. is cut out. The shim stock can "pull" from between the holding plates instead of cutting cleanly.
I would add a couple more locking bolts on the opposite side and give er a try.
I would add a couple more locking bolts on the opposite side and give er a try.
The two die plates need enough separation to slide the shim stock between them by hand. At first I caused the separation using washers between the plates but later milled a step into the top die plate to achieve the separation.
You slide the shim stock into the clearance slot between the die plates and punch the ID hole. Then you slide the shim stock ID hole to the die plate OD hole, align the OD punch with the ID hole in the shim stock using the OD punch nose step and punch the shim. Note the step (for better words) on the nose of the OD punch. That is used to align the shim stock ID hole with the OD die plate hole. Creating a cutting edge in that step was quite a challenge. I ended up using one of the small hand ground HSS tools you supplied with my lathe
Does that description make any sense at all???
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historicalarms
Ultra Member
Yes it does, it works identically to the pop can gas check cutter I built a few years ago from Youtube plans only I didn't have to cut an inside dia first, I just made discs. It had a sliding gap also and had the same problem you are having with ragged cut edges. I cut the alum. into strips and fed them into the die cutter one cut at a time. You could cut the shim stock into strips in your case then a couple of bolts on the opposite side wouldn't interfere with your feeding the shim stock in.
I think if I were building one I would forego the step between the two plates so they could be locked together. I would also put my cutter holes closer together, that way I could feed a strip in from one way and cut an inside dia. then an OD at the second hole all with one "pinch" then loosen the lock bolts and slide new shim material under the holes, lock down and cut in both holes. It will take a little longer in operation but I think the finished product will be better.
I think if I were building one I would forego the step between the two plates so they could be locked together. I would also put my cutter holes closer together, that way I could feed a strip in from one way and cut an inside dia. then an OD at the second hole all with one "pinch" then loosen the lock bolts and slide new shim material under the holes, lock down and cut in both holes. It will take a little longer in operation but I think the finished product will be better.
I tried clamping the shim stock between the die plates, it didn't help matters. I agree that supporting the shim gap on two sides would be a good idea though, especially, since I'm using mild steel for the die plates.
historicalarms
Ultra Member
The only shim stock I have ever used is in a hardened state, is there other "softer" stuff available . Cutting the 2 thou thick stuff I have would "roll" the sharp edge off mild steel in a very few cuts I think....I know you are searching for some hard plate and hope you find some.
It's pretty obvious that the material I'm using for the punches is way too soft. Note the amount of distortion occurring at the hammer end. The punches started out as PA cylinder pins. Strange stuff. Hard on the outside and gets progressively softer towards the middle.
At this point in time I'm in proof of concept mode. This morning I turned a new ID punch and bored the ID die plate hole to match. It would appear that I'm back to mangle mode again for some unknown reason.
If tapers are key here I sure didn't notice any on the commercial punch set I borrowed to clone.
The taper needs to be there or you're going to continue to have some serious issues. Die work requires a high degree of precision.
I still think for what you're doing a lathe like the video I posted above would be a better option unless you're making 1000 a day forever.
If you're intent on trying to do this as a punch die you're going to have to get into grinding probably or it might work for a little while and then stop working.
