Modifying shop press

[Monica]

I need to modify my 12T shop press but I could use some guidance on the proper way to go about it. The overall plan is to install a 1/2" plate (12"x12") on top and bottom for use as a clicker press.

Ideally would like to completely remove the crossmember/rod that the jack sits on. In it's place I'd like to put a new piece. I'd like to keep the stock crossmember together so I can use the press for its intended use if need be later down the line.

I sketched a rough idea but I don't have an engineer's mind. I need the steel plate to stay flat so it presses my dies evenly. I also need to attach the steel plate to the return springs without drilling through the plate so the press face stays clean and solid.

Ok, let me have it. Thanks

[GabZip]

What you have looks good. May want to put some gussets on the 1/2" plate.

[forhire]

I use a similar arrangement to install captive nuts around an 9" radius. I use 1" plates and it takes about 5 tons. Many pressing later and everything is still flat. I didn't modify my press, so I'm pressing from the center of the 1" plate. Half inch may or may not be stiff enough depending on your tonnage. Try it. If it bends you can straighten it and then sandwich another piece to stiffen it.

[fortyonethirty]

1/2" plates might not be thick enough. It probably will not bend permanently under 12 tons, but it might deflect during use and cause an incomplete cut. I'd recommend 1" or more. Also using thicker stock will allow you to weld to the back side without any warping. This is probably overkill, but overkill is better than having to repair it later.

[denrep]

With the proposed design, press force will attempt to crush a hollow tubular shaped cross-member; making a very heavy tube necessary. Of course forces should be exerted on the tube's vertical walls, not the flat.

Rather than rebuild the cross member from tube, I think it would be better to install a filler piece into the "C" of an original type channel cross-member, making the drop at least flush with the flange, and then attach the desired push plate to the filler.

Maybe the existing cross-member could be modified to work with both operations?

Good Luck

[MoonRise]

My suggestion?

Leave the original parts alone and ADD your desired flat plate to things. Just rig up a collar/socket that attaches to the original 'post' on the press.

Or just make your clicker die setup as a 'stand alone' item that just sits on top of the existing press table and is then squeezed down by the existing press 'post'.

And when you say "need the steel plate to stay flat", well once you start putting a load/force on the plate then it -will- start to deflect/bend. If the plate/die is beefy enough, then that deflection can be pretty darn small. But it would still be there. (small could be down in the less than a thou deflection for beefy dies.)

There is flat and then there is f-l-a-t. Your call as to which.

And the plate could deflect during use and then return to 'flat' once the force is released. That is what you want. Because if the pieces bend and stay bent, then the pieces have exceeded their yield point and they are no longer flat or whatever shape you wanted them to be in and stay in.

Hmmm, 12 tons and 1/2 inch plate? It probably won't fail totally (break apart) but it -could- bend a bit during use and -might- take a slight bend. Depending on exactly where the forces are going through things.

For a 12 x 12 x 1inch plate loaded with 12 tons (24,000 lbs) in the middle of the plate and "simply supported" (engineering term, pretty much means 'resting on the edges/end and not clamped or 'fixed' in place) on/near two edges, the plate will bend or deflect about 0.03 inches. 30 thousandths bending. The plate will spring back to 'flat' once the force is released.

For a 12 x 12 x 1/2 inch thick steel plate, same load of 12 tons, the plate would bend about 1/4 inch.

A plate 1/2 inch thick is only 1/8 as 'strong' as a 1 inch thick plate (sectional properties and the h^3 factor here).

Make it out of 1+ inch thick plate IMHO. Especially if you want things to stay or be flat during use.

[Monica]

I don't know if this changes any thing but more details here. I'll be using this for clicker dies on 6-8oz veg tan leather. The actual contact point footprint of die to leather is very small, and it is sharp at that.

Wouldn't this just be a case of the weaker material gets crushed first, or cut, as this case may be with the leather? I figure my leather will be cut long before metal parts give way, right? I appreciate the thorough discussion on it. My brain is probably not looking at the design structure as critically as other experienced eyes may be On the other hand, I don't want to miss the forest for the trees.

I'll be considering changing the plate thickness to 1". The compromise with 1/2" is its a fair function for the cost on these homebuilt presses. I'm still all ears.

Below is one of my dies.

[GabZip]

You could use a 1 ton press for what you are doing. I have seen cliker press with 3" air cylenders and 12" square platens used in production.

[Monica]

Originally Posted by denrep

With the proposed design, press force will attempt to crush a hollow tubular shaped cross-member; making a very heavy tube necessary. Of course forces should be exerted on the tube's vertical walls, not the flat.

Rather than rebuild the cross member from tube, I think it would be better to install a filler piece into the "C" of an original type channel cross-member, making the drop at least flush with the flange, and then attach the desired push plate to the filler.

Maybe the existing cross-member could be modified to work with both operations?

Good Luck

The existing crossmember is C-channel. So you're suggesting a solid piece as the crossmember on top of the plate instead of a hollow shape, right?

Originally Posted by MoonRise

Re: Modifying shop press
My suggestion?

Leave the original parts alone and ADD your desired flat plate to things. Just rig up a collar/socket that attaches to the original 'post' on the press.

That did cross my mind. But still leaves me with adding the plate. It seemed easier to build a nice dedicated crossmember instead of 'fixing' the existing parts.

Originally Posted by MoonRise

Or just make your clicker die setup as a 'stand alone' item that just sits on top of the existing press table and is then squeezed down by the existing press 'post'.

That's what I have now (only with a much smaller sized plate). The issue there is I only have one hand. Constantly placing/removing the plate on top of the die is cumbersome. It would be easier to have the plate attached to the crossmember so it retracts up and out of the way and I only need to handle my dies and leather.

Originally Posted by MoonRise

And when you say "need the steel plate to stay flat", well once you start putting a load/force on the plate then it -will- start to deflect/bend. If the plate/die is beefy enough, then that deflection can be pretty darn small. But it would still be there. (small could be down in the less than a thou deflection for beefy dies.)

There is flat and then there is f-l-a-t. Your call as to which.

I'd like as even a pressure across the die so it gets punched nice and straight. That makes the best cuts on my leather and prolongs the life of my die blades. If one edge is pressed deeper into the HDPE then it gets dull quicker than another area. The sharper the blade, the better the cut. I usually rotate the dies on the board each time so that the same shape is not pressed into the exact same spot.

[Monica]

Originally Posted by GabZip

You could use a 1 ton press for what you are doing. I have seen cliker press with 3" air cylenders and 12" square platens used in production.

Yeah, me too. I think 6T was as small as was going to when I was shopping. 12T was a decent price point for what I needed at this stage in the game. Compared to a $2k hydraulic clicker, this does the job just right. All my patterns are built well within the 12" x 12" area.

I've got a smaller bottle jack on the shalf. I bought the 12T so I could get an upgraded jack in the process (got a big truck, I could use the jack). Is the bigger jack causing a problem with the press design and what I want to do?

[ggarner]

At my friends work they use a clicker press for die cutting rubber to specific sizes and shapes. One thing I noted when I messed around on it there is that they use a high density foam under the rubber so that the die does not get bent from the large amount of pressure placed on it hitting something hard after the cutting is complete. Once it slices through the rubber it hits the foam travels a bit farther and stops. The die also has the same foam inside of it so that once the cut is complete the die pops back out of the material and the piece it cut also pops free on its own. Maybe something to consider so you dont mess up your dies. The rubber that they cut is quite tough so I would guess its pretty similar to leather in that way. Just some food for thought.\

looks something like this

[Monica]

Originally Posted by ggarner

At my friends work they use a clicker press for die cutting rubber to specific sizes and shapes. One thing I noted when I messed around on it there is that they use a high density foam under the rubber so that the die does not get bent from the large amount of pressure placed on it hitting something hard after the cutting is complete. Once it slices through the rubber it hits the foam travels a bit farther and stops. The die also has the same foam inside of it so that once the cut is complete the die pops back out of the material and the piece it cut also pops free on its own. Maybe something to consider so you dont mess up your dies. The rubber that they cut is quite tough so I would guess its pretty similar to leather in that way. Just some food for thought.\

looks something like this

lol yeah, those are the expensive clickers

I use HDPE under the leather. Leather needs to have a solid form underneath or it doesn't get cut properly. The 'cutting board is soft enough it doesn't kill the die quickly. The other piece to that is having a quality die.

[MoonRise]

Monica,

Maybe think of setting up your die 'rig' like a 'real' tool die.

In words,

- make a bottom plate, that has some beefy pins/posts at the corners;

- make a top plate that can ride up and down over those pins/posts;

- your 'cookie cutter' die attaches to the top plate/platen;

In use, the lower platen would have your backing board of HDPE/plastic put on top of it (if you rig it up to also be located by the corner posts/pins, it won't shift around), then the piece of leather is put on top of that. The upper plate/platen can either be attached via collar/socket to the 'post' of the press or it could just be part of the die set. If part of the die set, you would probably want to put some springs into the die set so that the upper plate/platen rises up from the springs when the press is not pressing down. Use the press to push down on the die and cut/stamp your leather.

[ZTFab]

Something like this Moonrise??

[ggarner]

Originally Posted by Monica

lol yeah, those are the expensive clickers

I use HDPE under the leather. Leather needs to have a solid form underneath or it doesn't get cut properly. The 'cutting board is soft enough it doesn't kill the die quickly. The other piece to that is having a quality die.

Ahh yea that makes sense! So what do you do with these Texas shaped pieces of leather? Any pics?

They ended up going with that hydraulic clicker because when they do production runs sometimes some poor sob has to sit there for 8 hours a day clicking away.

[Monica]

Very cool. Now, let me introduce a hitch. - I have multiple dies. And right now I'm not even close to having a die for every pattern I use.

[ZTFab]

Originally Posted by Monica

Very cool. Now, let me introduce a hitch. - I have multiple dies. And right now I'm not even close to having a die for every pattern I use.

Do you make the dies??

I would try to incorporate a common mounting system into all of the dies. Something that is the same on each die that has a corresponding piece on the top die of the press to mount them to.

[Monica]

Originally Posted by ZTFab

Do you make the dies??

I would try to incorporate a common mounting system into all of the dies. Something that is the same on each die that has a corresponding piece on the top die of the press to mount them to.

No, I do not make the dies.

I guess I'd need one heckuva on/off magnet eh?

Originally Posted by ggarner

Ahh yea that makes sense! So what do you do with these Texas shaped pieces of leather? Any pics?

They ended up going with that hydraulic clicker because when they do production runs sometimes some poor sob has to sit there for 8 hours a day clicking away.

That die I posted builds the holster in this picture (the ranch brand is a customer's, not my own).

[ZTFab]

Originally Posted by Monica

No, I do not make the dies.

I guess I'd need one heckuva on/off magnet eh?






That die I posted builds the holster in this picture (the ranch brand is a customer's, not my own).

Nice holster!!!

Is there any commonality to the dies? Like the square stock braces used in the center? Any common dimensions, etc...?

[Monica]

Thanks

[MoonRise]

Paul - ZTFab,

I can't see your photobucket attachment. Corp firewall won't let it through.

Monica,

Attaching a cutter to the die upper plate/platen could be as simple as just a few small screws through the 'cross brace' on the top of the cutter into the upper plate/platen. If most of the cutters are of a similar overall size, then try to standardize the screw hole placement or put the mounting screw hole in a standardized grid pattern of some sort and maybe make up a drilling/spacing jig to make the process of making the holes all the same faster and repeatable.

Sort of like this. The red dots are where holes go through the cutter die 'straps' and have some small(er) screws attaching to the bottom of the upper plate/platen. "Small' as in probably -not- a 3/4 bolt. Maybe more like a 10-32 screw. Something like a button-head cap screw would help to minimize any possible 'marking' of the material being cut/stamped if it pushed all the way up to the top of the cutter. As opposed to say a plain slotted screw head that maybe got buggered up and has a burr on it that then makes a mark onto your leather pieces.

[ZTFab]

Originally Posted by MoonRise

Paul - ZTFab,

I can't see your photobucket attachment. Corp firewall won't let it through.

How's this?

[MoonRise]

Paul,

Yup, that image attachment shows up now.

Same thing I posted/described, except your pic shows it in 3-D.

And you put some nice rounds on the edges of all the plates too. And a chamfer on the top of the pins. And a nice helical spring as well. Some of the diagonal lines are showing some aliasing though.

btw, what software did you use to whip up that concept in?

[ZTFab]

That's SolidWorks 2010

As far as the aliasing lines go...I can't do anything for crappy video cards!!

It must be something with the image transfer. It looks that way to me too when saved as a jpeg.

[GabZip]

You are not dealing with uniform sheet metal blanks. Leather has imperfections and is irregular in shape. The method OP was using has been worked out over the last 2-3 hundred years. The guide posts would just get in the way.