Building a High Speed Punch Press

[Karl_T]

Always interesting to see how an expert does a job...

Couple questions

Looks like you are machining dry - why?

I've always used AL plate or stand off blocks to mount to a mill for this type application. Any advantage to wood/mdf or just cost? I'd always assumed wood chips, steel chips, and coolant to not work and play well together.

Karl

 

[JimDawson]

Expert? Not sure about that, but thank you Karl.

In the cast iron of the press frame, yes, I was cutting dry. Most cast pretty much self lubricates due to the free carbon content. Sometimes I use an air blast, but in this case, I just used the shop-vac to suck up the chips.

In the steel, I was not machining dry. There is a mist there, you just can't see it in the photos. My no-fog mister works pretty good, pretty much adjustable between 0 and flood. In this case I was using WD-40 because that is what I had in the tank. I need to build another tank system so I can switch between coolants. I machine a lot more AL than I do steel.

Absolutely cost, MDF is cheap. Like you I use AL plate and/or standoff for production work. But for one-off parts, MDF works great. It's dimensionally stable when well supported. MDF is pretty tough stuff in compression, and drills and taps OK to keep parts from moving laterally, in tension it's not very good, but for light milling using deck screws to hold the part down it works well. It resists coolant pretty well in the short term and I normally use minimal coolant.

 

[Reeltor]

Very interesting discussion about using MDF under the work to be machined. I'm looking forward to hearing more.

Mike

 

[JimDawson]

A bit more work on the press project today


This is the front support plate. It will have a bore for a ball bearing and some clearance milled for the cam follower carrier. Again this is mounted up on a chunk of MDF and through bolted to the T-slots.


I could cut the parts with the bandsaw, square them up, locate the edges precisely, then drill the hole pattern, or just do all of those operations in one setup. This could be done the same way on a manual machine as a CNC. For the bearing bore and the other machining I will put them in the vice.





The next batch of parts is made of 0.500, C1018 steel. There are 5 pieces: 2 side plates, 1 top plate and a pair of cam follower carriers. Again I could have done all of separately, but there are less steps and fewer tool changes when doing them all at once in one setup. There will be a secondary operation on the cam follower carriers to bore the pin hole, but that will be done once they are welded to the ram. I was able to put in ‘’lubrication access holes’’, which just happened to exactly fit the T-slot spacing.:whistle:


I set up the material as I described in a previous post. The one addition that I did here is to put a small mark with a center drill at a known location for a datum point. We had pretty good winds today and I was afraid that we might lose power. This is the down side of using this method to place the material in that I have no idea exactly where the edges are at with out actually measuring. Thus the witness mark in case I lose the 0. I could locate this mark with either the pointy end of an edge finder or a spindle microscope.










First center drill and pilot drill, and final drill the hold down cap screw locations, then install the hold down bolts.





Then center drill and pilot drill, and final drill the rest of the holes. The 3/8 and ¼ inch cap screws are threaded into the MDF. Because there is only one hold down cap screw per part I did this to prevent the part from possibly twisting. The 3/8 and ¼ holes are used in the final assembly so they serve a dual purpose. It is now set up and ready to start cutting out parts.





First I cut out the big chunks to minimize waste and to get them out of the way. Then made the roughing pass leaving 0.020 for final clean up. Then a clean up pass to finish. After deburing and countersinking the holes, the plates are complete.





Now all of the parts are cut out and drilled. Tomorrow I’ll do the secondary operations on the parts that need it.

 

[JimDawson]

A little more progress today

The pockets in the front plate are done, just have to finish the bearing bore with the boring bar. That hole was not supposed to go all the way through, there was supposed to be a 0.109 flange left but the material vendor screwed up and delivered 7/8 thick material rather than the 1 inch I ordered and I didn't catch it, so my bad. The mark of a machinist it to be able to make a f&*^ up look like it was supposed to have been done that way. So I’ll make a nice cap for it and use that for the limit switch cam guard, nobody but us will ever know the difference.:lmao:



Pocketing the motor mount. C1018 steel, 3/8 solid carbide, 2 flute, end mill. 2200 RPM spindle speed, 0.125 DOC, 5 IPM. WD-40 in the spray mist.



Wading through the clearance slot in one pass. 3/8, 3 flute cobalt rougher, 900 RPM, 0.75 DOC. 0.5 IPM



Finishing the bearing bore. I wanted a nice light press fit, so I bored the pocket to the bearing size –0.0002. I maybe could have done with the mill, but the boring bar is much easier to control to a fine dimension. 70 RPM, brazed carbide boring bar, 0.5 IPM down feed. This is the first boring job (there is a reason they call it boring) I have done since I did my Z-axis conversion. It’s great to be able to change both the spindle speed and the down feed on the fly. Was able to tune it right in for no chatter:thumbsup:

 

[Eddyde]

Great work Jim, I can't understand why your client wants to us a HF press for a base, when clearly you could build a much better press from scratch. It is like putting a Rolls Royce engine in a Ford Pinto.

 

[JimDawson]

Great work Jim, I can't understand why your client wants to us a HF press for a base, when clearly you could build a much better press from scratch. It is like putting a Rolls Royce engine in a Ford Pinto.

Thank you for the kind words.

I tried to talk him out of it, and it would have been easier to build one from the ground up. Sometimes you just have to follow the customer's lead. When this one breaks, I'll do it my way on the next one and he can pay for it again. Job security I guess.

I had a potential customer call me yesterday and wanted to modify a 4x8 CNC wood router to a 6x12. Fortunately I was able to talk him out of that, the modification would cost more than building a gantry router from the ground up. I see building a 6x12 CNC router in my future.

 

[JimDawson]

I assembled the parts I have built just to check the fit. It seems to go together, but I'll have to do a bit more precision fitting.

 

[randyc]

Man, I can't believe that thing will achieve 600 strokes/minute, must be punching some real thin material to be able to keep the flywheel spooled up (or maybe it doesn't have a flywheel like a conventional punch press). At ten hits per second, that HF thing is going to wear out pretty dang fast, right ?

Oh well, since your customer made some poor decisions I expect you'll get some more business from him in REPAIRS, LOL. Nice work !

 

[JimDawson]

Man, I can't believe that thing will achieve 600 strokes/minute, must be punching some real thin material to be able to keep the flywheel spooled up (or maybe it doesn't have a flywheel like a conventional punch press). At ten hits per second, that HF thing is going to wear out pretty dang fast, right ?

Oh well, since your customer made some poor decisions I expect you'll get some more business from him in REPAIRS, LOL. Nice work !

Thank you Randy

I had the forethought to work backward on the design. The powerhead will bolt right in to a press frame that I designed first, then adapted the mounting to the HF press. So when this one breaks, I can take the parts and install them in the new frame.

There is no flywheel, the actuating cam is direct drive from the 4200 oz-in stepper motor. The required ''tonnage'' is in the 400 lb range. I had to use a cam rather than a crank because I had to maximize the open time, I managed to get 220 degrees of on-top time and still keep the the ramps reasonable.

When I get it done, I'll try to post a video of it running. Unfortunately, I won't be able to show it with the tooling or in actual use.