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  #1  
Old 12-31-2019, 06:51 PM
Jon Thompson Jon Thompson is offline
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Default WTB Pullmax P9 Center Tool Holder

Looking for a P9 lower center tool holder 25MM.

Last edited by Jon Thompson; 12-31-2019 at 09:59 PM.
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  #2  
Old 01-01-2020, 03:27 AM
metal manny metal manny is offline
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Hi Jon, I assume that you already have an off-centre tool holder used primarily for cutting sheet?
As you probably already know, Pullmax parts are rare don't come without a premium price. A solution worth considering is machining up a simple adapter plate (shown in red) which will give you the option of running an off-centre toolpost in both centre and off-centre positions as depicted in the drawing. For my adapter (P-21 machine) I purchased 25mm/1" bright mild plate, which was the offset required, milled to accommodate the keyways and bolt holes... Let me know if you need more info.

Plate front.jpg

Plate back.jpg
Attached Files
File Type: pdf Pullmax adaptor.pdf (385.2 KB, 9 views)
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Last edited by galooph; 01-01-2020 at 05:54 AM.
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Old 01-03-2020, 06:48 AM
Jon Thompson Jon Thompson is offline
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Manny yes I have had that exact solution in there for over twenty years and it works great. However we are duplicating some inner frame rails and need to stretch .074 AKDQ returns up to approximately 1.125' wide. So in the past I have built lineal stretch dies but because of the offset lower tool holder the beak style dies are almost 3" from the tooling center and because of the leverage due to the offset they are not very efficient. Those dies were for .045".. Now I need to influence .074". I did a piece of .060 CQ higher carbon content with a direct center die over center die with a flat 1" (25mm) lower and a profiled upper approximately .125" by .625" contact area and it worked very well. So it's the interference of the lower tool holder that is the problem. Even with a center lower tool holder they will still be off set beak style dies. Thanks for your offer to help though. Jon
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Old 01-03-2020, 06:53 AM
Jon Thompson Jon Thompson is offline
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I am also wondering if my lower tool holder is worn. The obvious flex is in the actual tool holders. Jon
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Old 01-04-2020, 04:04 AM
metal manny metal manny is offline
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Possibly a wear issue as you mention, although the forces being generated 3" off centre on thicker gauge steel will test any tooling, IMO.

However, as it seems that the problem you're encountering seems to be restricted mainly to the fabrication of this part, and using the beak-style dies, have you considered getting a new tool holder machined (in the light of scarcity and premium prices) and using your existing collet and nut? Failing which, could you perhaps borrow a holder from another shaper/shop in your area?
I bought my P-21 with a centred tool post, and happened chance upon a second very cheap machine which I snapped up solely for the off-centre tool post - which I've never used!
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Old 01-04-2020, 04:47 PM
norson norson is online now
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If it's a one off I'd use an anvil or railroad track and a BF hammer.
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Old 01-05-2020, 08:42 AM
Jon Thompson Jon Thompson is offline
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Manny yes that is the solution we have come up with. Direct die over die via a weldment machined to temporarily replace the existing pullmax component. I am considering using off the shelf lineal stretch dies along the lines (die size and post) of a Cal Davis style hammer. Possibly we will machine a custom set. My knowledge of material selection has been gained purely by trial and error. I have had dies machined out of S7 but they were not post machining hardened. Nearly all of the pullmax dies we have built in house. To call them tooling is a stretch. I am only concerned with function. This situation is a little bit different. The P9 will certainly be overkill for this application but the dies I think will need to be robust. Thinking about contact area. Should it taper from outside to inside to match how the stretch actually occurs? Also to keep the custom tool holder low profile at the functional die area (clearance for the C style channel) I am thinking about giving the holder itself the vertical adjustment function versus a taller post with an adjuster closer to the die and interference. Thinking and doing this phase makes my socks roll up and down, fun...
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Old 01-06-2020, 02:10 AM
metal manny metal manny is offline
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Jon, I don't think the die needs to be tapered. If you look closely at linear stretch dies, they normally have a parallel contact area similar to a cold chisel. One works the outer edge of the material being stretched a little more than the inner edge to achieve the level of stretch required using multiple medium to light blows.

Most of our machine tooling is crudely cobbled together for these little one-offs, but works just fine in my experience.
Just a thought... Why don't you make your stretch die from an appropriately modified cold chisel/hammer head or other existing hardened material? That'll quickly circumnavigate steel choice, tempering etc, and get you fabricating pronto.
Please post your results with accompanying pics so we can all learn from your solution.
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Old 01-06-2020, 08:42 AM
Jon Thompson Jon Thompson is offline
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Manny Yes I am aware of the method and existing die profiles. I was thinking along the lines of a single blow doing what would be the V patterns I use now. You are probably right, just keep it simple. I would be happy to document and share what we come up the good and bad. Thanks Jon
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