TECH - Building a Pullmax-Style Hammer

kman1932 · Mar 6, 2010

NICE job!!!!!!!! You got my vote

Brad S. · Mar 6, 2010

Wow Drew. That's badass.

Telting · Apr 2, 2020

bigDrew said: ↑

Here is my entry for Tech Week. Tech articles are the coolest and I wish there were more of them on the HAMB!!

I decided to build a Pullmax-style reciprocating machine for three main reasons. 1) Im too cheap to cough up the $6k needed to buy a new one 2) Ive got my mind made up that my next hot rod Im going to build from scratch and 3) the Pullmax-style hammer is a very proven and versatile design. My design incorporated 0.750 (19mm) tool holder shafts which makes it compatible with all commercially available Pullmax tooling. I dont think that you could (easily) build a power hammer without access to a machine shop.

Ill include a complete BOM and drawings at the end of this thread. Since most of the material used is pretty short you could probably pickup some drops pretty cheaply from your local steel yard or machine shop. The total cost for my build is $400 because I had almost all the material lying around.

NOTE: Most of my inspiration and some of the design came from the guys at the www.metalmeet.com and http://allmetalshaping.com forums. If you have not checked out those sites you should. The stuff that those guys can create with metal is pretty amazing.

This is not a tutorial in how to use a mill and lathe. If you have a mill and a lathe I assume you know how to operate them!!

Step 1: Upper tool holder slide
This is the business end of the hammer as most of the assembly is stationary. This was made from a billet piece of aluminum that I had lying around. This could be made from steel, but aluminum is much easier to bore and this piece does not really see any force as the hammer shaft should always float between the bearings because the stroke is limited by the offset in the driveshaft. The orientation of the upper and lower dies is critical if you are running shrinking dies. If you have any mis-alignment during the hammering you will get marks in the piece you are shrinking. In theory the connecting link will keep the shaft oriented correctly, but I wanted to make sure there was not any deflection or movement. I came up with a slotted design that uses roller bearings to keep everything oriented. The roller bearings are cheap and easy to replace when they wear out. I used commercially available bushings for the shaft to ride on because they are cheap and easily replaced when they wear out.

The upper tool holder slide must be bored for the bushings. A slight press fit will do the trick.

Holes are drilled and tapped into the block. A slot is milled on each side for the needle roller bearings to ride in. This will keep the upper tool holder oriented during operations.

Machining completed with bushings installed

Step 2: Upper tool holder
The design of the upper tool holder has to address the tricky square-in-a-round-hole problem. It is slightly more complicated than the lower tool holder because the shaft has to move up and down. I cheated on this design and purchased a square collet from Reid Supply. This was built from a 7.5 long piece of 4130 material I had from another project. The square collet was welded into the upper tool holder to ensure perfect alignment once everything was assembled. The tool post bottoms out against the bottom of the bore so they weld does not carry any load it just orients everything correctly until the clamp is applied. The clamp was made from a shaft collar. The shaft collar was secured to the upper tool holder and then the holes were drilled and tapped through. In theory I could have made the upper tool holder out of a large OD piece of material instead of using the shaft collar, but Im too lazy to turn down the OD that much. The machining of this was fairly easy because I have an indexing vise, but it could be done with a standard vise if you lay everything out properly.

The shaft OD is turned and polished on a lathe.

The slot for the connecting rod is milled out.

Hole is drilled for the connecting rod bolt and flats are milled. The flats are only for the bolt and nut to shoulder against.

Holes are drilled and tapped into the shaft collar. These set screw will provide the clamping force on the square collet.

Machining complete

Completed assembly showing the needle roller bearings. The design uses two bearings one for the upper tool holder slide and one for the frame. The shows the collet after it was welded in. The weld does not carry any load all the hammer load is transferred to the bottom of the bore.

Step 3: Lower tool holder
This is my version of the design that TheRodDoc posted on the metalmeet.com forum. His design greatly simplified the square-in-a-round-hole problem and was easily built with material I had lying around. I did not have a chunk of steel this big so this was made out of multiple pieces of flat bar. They are pinned/welded together and them all squared up in the mill. Once the cover plate is bolted on nothing can move. This must be made of out of steel because it carries a considerable amount of load.

Flat bar welded together and squared in the mill.

Drilling and tapping the holes

Machining completed with tool shaft installed. The height of the side was milled down so the cover plate can clamp tightly against the tool shaft.

Cover plate

Bottom plate which will be welded in place

Completed assembly

Completed assembly with adjustment screw installed. Since I dont have a 3/4" 6 stub acme tap I just welded a nut. The welding was done with the cover plate installed to make sure everything stayed lined up.

Step 4: The frame
I had originally planned to have the frame waterjet from 1 steel. This could have left a clean edge and eliminated any heat affected zone. I got three quotes and they were all around $450-500 per plate so I decided to use some 3/4" x 4 flat bar that I had lying around. If my frame did not work I would spend the money. I can send you .dxf version of the frame if you want to get it cut out. The only thing that is super critical on the frame is the alignment of the top and bottom tool holders. It could easily be made from square or rectangular stock.

The same bolt pattern and slots were machined into the top arm. The needle bearings can easily be changed out without taking the head apart if needed.

Step 5: Assembling the frame
Once everything is bolted together a piece of key stock was inserted into the tool holders and then the square collet in the top tool holder was welded in place. This assured perfect alignment between the two tool holders.

I waited to box/weld the frame together to make sure the alignment was perfect.

Click to expand...

Telting · Apr 2, 2020

bigDrew said: ↑

Here is my entry for Tech Week. Tech articles are the coolest and I wish there were more of them on the HAMB!!

I decided to build a Pullmax-style reciprocating machine for three main reasons. 1) Im too cheap to cough up the $6k needed to buy a new one 2) Ive got my mind made up that my next hot rod Im going to build from scratch and 3) the Pullmax-style hammer is a very proven and versatile design. My design incorporated 0.750 (19mm) tool holder shafts which makes it compatible with all commercially available Pullmax tooling. I dont think that you could (easily) build a power hammer without access to a machine shop.

Ill include a complete BOM and drawings at the end of this thread. Since most of the material used is pretty short you could probably pickup some drops pretty cheaply from your local steel yard or machine shop. The total cost for my build is $400 because I had almost all the material lying around.

NOTE: Most of my inspiration and some of the design came from the guys at the www.metalmeet.com and http://allmetalshaping.com forums. If you have not checked out those sites you should. The stuff that those guys can create with metal is pretty amazing.

This is not a tutorial in how to use a mill and lathe. If you have a mill and a lathe I assume you know how to operate them!!

Step 1: Upper tool holder slide
This is the business end of the hammer as most of the assembly is stationary. This was made from a billet piece of aluminum that I had lying around. This could be made from steel, but aluminum is much easier to bore and this piece does not really see any force as the hammer shaft should always float between the bearings because the stroke is limited by the offset in the driveshaft. The orientation of the upper and lower dies is critical if you are running shrinking dies. If you have any mis-alignment during the hammering you will get marks in the piece you are shrinking. In theory the connecting link will keep the shaft oriented correctly, but I wanted to make sure there was not any deflection or movement. I came up with a slotted design that uses roller bearings to keep everything oriented. The roller bearings are cheap and easy to replace when they wear out. I used commercially available bushings for the shaft to ride on because they are cheap and easily replaced when they wear out.

The upper tool holder slide must be bored for the bushings. A slight press fit will do the trick.

Holes are drilled and tapped into the block. A slot is milled on each side for the needle roller bearings to ride in. This will keep the upper tool holder oriented during operations.

Machining completed with bushings installed

Step 2: Upper tool holder
The design of the upper tool holder has to address the tricky square-in-a-round-hole problem. It is slightly more complicated than the lower tool holder because the shaft has to move up and down. I cheated on this design and purchased a square collet from Reid Supply. This was built from a 7.5 long piece of 4130 material I had from another project. The square collet was welded into the upper tool holder to ensure perfect alignment once everything was assembled. The tool post bottoms out against the bottom of the bore so they weld does not carry any load it just orients everything correctly until the clamp is applied. The clamp was made from a shaft collar. The shaft collar was secured to the upper tool holder and then the holes were drilled and tapped through. In theory I could have made the upper tool holder out of a large OD piece of material instead of using the shaft collar, but Im too lazy to turn down the OD that much. The machining of this was fairly easy because I have an indexing vise, but it could be done with a standard vise if you lay everything out properly.

The shaft OD is turned and polished on a lathe.

The slot for the connecting rod is milled out.

Hole is drilled for the connecting rod bolt and flats are milled. The flats are only for the bolt and nut to shoulder against.

Holes are drilled and tapped into the shaft collar. These set screw will provide the clamping force on the square collet.

Machining complete

Completed assembly showing the needle roller bearings. The design uses two bearings one for the upper tool holder slide and one for the frame. The shows the collet after it was welded in. The weld does not carry any load all the hammer load is transferred to the bottom of the bore.

Step 3: Lower tool holder
This is my version of the design that TheRodDoc posted on the metalmeet.com forum. His design greatly simplified the square-in-a-round-hole problem and was easily built with material I had lying around. I did not have a chunk of steel this big so this was made out of multiple pieces of flat bar. They are pinned/welded together and them all squared up in the mill. Once the cover plate is bolted on nothing can move. This must be made of out of steel because it carries a considerable amount of load.

Flat bar welded together and squared in the mill.

Drilling and tapping the holes

Machining completed with tool shaft installed. The height of the side was milled down so the cover plate can clamp tightly against the tool shaft.

Cover plate

Bottom plate which will be welded in place

Completed assembly

Completed assembly with adjustment screw installed. Since I dont have a 3/4" 6 stub acme tap I just welded a nut. The welding was done with the cover plate installed to make sure everything stayed lined up.

Step 4: The frame
I had originally planned to have the frame waterjet from 1 steel. This could have left a clean edge and eliminated any heat affected zone. I got three quotes and they were all around $450-500 per plate so I decided to use some 3/4" x 4 flat bar that I had lying around. If my frame did not work I would spend the money. I can send you .dxf version of the frame if you want to get it cut out. The only thing that is super critical on the frame is the alignment of the top and bottom tool holders. It could easily be made from square or rectangular stock.

The same bolt pattern and slots were machined into the top arm. The needle bearings can easily be changed out without taking the head apart if needed.

Step 5: Assembling the frame
Once everything is bolted together a piece of key stock was inserted into the tool holders and then the square collet in the top tool holder was welded in place. This assured perfect alignment between the two tool holders.

I waited to box/weld the frame together to make sure the alignment was perfect.

Click to expand...

Telting · Apr 2, 2020

Drew, if I could get the .dxf files that would be great as I happen to have a plasma table... much appreciated

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TECH - Building a Pullmax-Style Hammer

kman1932
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from fairview, pa.

Brad S.
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from Houston, Texas

Telting

Telting

Telting

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TECH - Building a Pullmax-Style Hammer

kman1932 Member from fairview, pa.

Brad S. Member from Houston, Texas

Telting

Telting

Telting

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kman1932
Member

from fairview, pa.

Brad S.
Member

from Houston, Texas