die/punch alignment for kickpress and thin material

I have a Whitney 5 ton kickpress and need to punch 3/8" holes in 0.040 thick aluminum that is preformed into an 8" deep channel about 8" wide (holes in the bottom). I was hoping the gibs of the press (which are well adjusted and tight) would provide the alignment needed. But the flex of the press frame seems to allow the bottom platform to move down slightly (about 0.005") relative to the ram and in moving to move down slightly more on the front than the back. This causes the pedestal that fits into the upside down channel to spring forward about 0.010" - much more than the clearance of the die. I have very little experience with this sort of thing. I am thinking a die set is needed but it would need to be a fairly large one.

Currently drilling with a step drill but it produces a large, difficult to remove burr on the back side and is slow.

Yes....you are right....you need a die set to ensure the top tool aligns with the bottom tool or you'll "nip" the sides of the bottom die and destroy it.

A die set can be made simply by having a steel bottom plate with two or four pillars sliding in 2 or 4 bushes in a top steel plate.......if you have a mill and tool making experience or knowledge.
Ian.

I get the basic idea of a die set for alignment. But the issue I see is that if the press frame flexes and the die set is firmly fastened to the press (both top and bottom) that the press frame deflection will tend to move things out of alignment and the die set will try to keep things in alignment. The result will be something in the middle with less but still some misalignment. Or is the die set mounted so that only downward pressure is transferred to the die set? I have seen some small punches that are pressed down with a ball bearing so that any flex is not transferred to the punch but doubt that is common.

Hi.....a press normally is made rigid enough to not move about with die sets.......even then the slides still have some slackness so a die set in any press is the way to go.....it also makes tool changes easier as the tools for the particular job are mounted in the die set and stay with it when removed from the press.

If the press is the normal shop type press, with just a bottle jack up top and a pair of steel plates on the beam, which is located on the uprights with pins and can slide up and down for height adjustment, then you would/must have a flexible interface between the ram of the jack and the top of the die set......the ram of the jack can just press down on the dies set top, but you will need some springs to make the top of the die set rise after the work is punched......normally the ram of the press would pull the top of the die set up.

In place of springs you could make the ram interface a loose but constrained fit to enable it to pull the top of the die set up......even then,the springs normally fitted to a shop type press may not be strong enough to pull the tool out of the punched work piece.
Ian.

Using a properly sized die set will pretty much eliminate the flex in a kick press. Find something with 1 inch or larger pins. http://www.promsnab.info/catalogues/...bigcatalog.pdf

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Originally Posted by Jim27

I get the basic idea of a die set for alignment. But the issue I see is that if the press frame flexes and the die set is firmly fastened to the press (both top and bottom) that the press frame deflection will tend to move things out of alignment and the die set will try to keep things in alignment. The result will be something in the middle with less but still some misalignment. Or is the die set mounted so that only downward pressure is transferred to the die set? I have seen some small punches that are pressed down with a ball bearing so that any flex is not transferred to the punch but doubt that is common.

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I have a large'ish fly press and there's no flex at all in it, but as others have pointed out a proper die set will eliminate any alignment issues anyway. As you asked above, the press will provide downward pressure and die sets are normally bolted/clamped to the table, so any sideways movement doesn't usually matter at all then.

cheers, Ian

Hi.....with most presses designed to do press tool work.....fly presses kick presses and all power presses that have a flywheel driving a ram down. the ram is mostly guided by dovetails or square slides which do keep them fairly in line, but if you have punch tooling that has .04mm clearance then a die set is imperitive not optional........with form work where you do bending etc, the tolerances are not so critical in most cases.
Ian.

Die Sets - Custom Die Sets, Standard Die Sets, Cast Die Sets - Anchor Danly

The problem is going to be finding a die set that will handle 8" deep channel that will fit in your 5 ton kick press ...

You will most likely have to make on specific to your application.

Hey.....just re-read the first post again.....3/8" holes are peanuts for a 5 ton press and shouldn't make the frame deflect at all......if it does.....on a 5 ton press?????.......... you have the effect of a channel laid on it's side and the bottom piece flexing away.

To cure this deflection effect and also to prevent open face C type press frames from breaking the back of the press, a front brace is attached to the top of the ram housing and the bottom of the base at the front.

This does close in the press access a bit for wide work, which has to be presented into the front of the press, but if the work piece is narrow enough to be inserted into the press from the side, I'd examine the press frame to see if a brace could be fitted ........even if it meant "modifying" the press frame slightly to attach a brace ......couple of tapped holes etc.

The brace is nothing more than a piece of flat steel strip with a hole for bolts at each end.......steel has 27 tons per sq inch tensile strength so a piece of steel flat strip 1" wide by 1/4" thick and 1/2" diam high tensile bolts would do the trick.

A photo of the press would make designing the brace and attaching it easier.
Ian.

I see there were a number of posts after I solved this issue. The issue was that the platform was tipping slightly with the pressure and with the 8+ inch high post with die on top it was moving forward. I put a narrow strip under the die post so it could pivot forward and back. Then put some large end plates on each side with large holes for the 8" channel. Then tied the top of the end plates to the top of the press but with some ability to flex up and down but not forward and back. The post, end plates, etc all made of wood. Works great and was easy to put together cheaply with what I had on hand. This particular model of kickpress had a detachable platform so I was able to make something lower with more height clearance.