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Spencer 02-02-2019 09:40 AM

75 Ton Electric Hydraulic Shop Press
 
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I'll be picking up a used Owatonna Tool Company (OTC) 75 ton shop press on Monday that I bought via online auction.

I was able to inspect the press in person before bidding on it and was pretty happy with most of what I saw. I'll get into some of the things I was not happy to see later on, but for now I have a question I hope some of you can answer about the cylinder.

The hydraulic cylinder on the press has threads on the bottom, which I was not expecting to see. I've had very limited exposure to shop presses, especially good sized units such as this, but I just don't recall ever seeing one with threads.

Are threads common on larger shop presses? The seller was clear that he was keeping most of the fixtures and jigs that had been used with this press, as he plans on converting them for use with the Ironworker that will assume all responsibilities that this press had previously handled. I convinced him to include the press plates for this, but that was not easy and I was so happy to have got him to throw those in that I didn't want to press my luck any further.

One of the fixtures he showed me he was in the process of converting obviously had some type of attachment point previously welded to the top of it. I assume that had female threads on it to match the male threads on the cylinder, but we never discussed that piece and I fear it may have been ruined when it was removed. I'll obviously bring the threaded adapter or whatever the correct term may be on Monday when I am there to pick up the press, but I'm not holding my breath.

I can't find any information on OTC's website. I'll be reaching out to them sometime next week as time permits, but in the mean time I'm curious just how screwed I may be in trying to find the proper threaded adapter I'd need to fit this cylinder.

If I can find a threaded adapter I'm assuming it may cost a small fortune. OTC doesn't seem to make a 75 Ton press anymore, it looks like they go straight from a 55 Ton to a 100 Ton. I found the manuals and parts lists for those units and there is no hint of threads on the bottom of those cylinders.

Their replacement 55 Ton cylinder sells for $4,550 and the 100 Ton goes for $7,666, so I definitely don't want to damage this 75 Ton cylinder by screwing up those threads.

I've attached a photo of the cylinder, which shows the threads in question. If anyone knows of a source to purchase a threaded adapter suitable for 75 tons of force I would appreciate it. Even just the proper term for the adapter would help me out.

MetalWolf 02-02-2019 10:08 AM

You could take off the cylinder and take it to a cylinder shop have the old style thread cut off and the newer or more recent thread piece rewelded back on...
I've had to do this to smaller cylinders before... for sure would be a bit pricy but not as pricy as buying a new cylinder...

digr 02-02-2019 11:42 AM

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First thing that I would would do is measure the thread pitch and and diameter then make threaded collars or if you can buy nuts to fit the rod with flat plate welded to nuts or collars. This will work as long as the threads on the ram bottom out on the plate. Or what I did with mine was to turn the end of the ram down to receive slip on collars held with a set screw which is nice when you have to make different adapters.

Shade Tree Welder 02-02-2019 12:58 PM

Quote:

Originally Posted by digr (Post 729768)
First thing that I would would do is measure the thread pitch and and diameter then make threaded collars or if you can buy nuts to fit the rod with flat plate welded to nuts or collars. This will work as long as the threads on the ram bottom out on the plate. Or what I did with mine was to turn the end of the ram down to receive slip on collars held with a set screw which is nice when you have to make different adapters.

I concur, what ever you do make sure you don't transmit the force
through the threads. You will not be happy with that result!

milomilo 02-02-2019 01:50 PM

Like STW says, no force on the threads. The threads are only to attach something to the ram and not have it fall off. Whatever you attach has to bottom out on the end of the ram so all the force is on the ram via the item on the end of the ram, and none on the threads. You can make your own adapter and thread on a lathe to match the ram threads.

LKeithR 02-02-2019 02:11 PM

It's not uncommon to find threads on the end of press cylinders, especially older, heavier stuff. As others have said you must ensure that any pressing forces are on the end of the ram and not on the threads. Although the press we have right now has internal threads on the end of the ram I prefer slip-on type tools; they're much faster to change than threaded types. If you've got an inch or more of fine thread it takes a while to run one adapter off and another one on. And you never want to press directly against the end of the thread--it doesn't take much to mushroom the end and then you've got a problem as well.

As far as the press is concerned you won't find anything better than OTC. They make (made?) good stuff. What other things did you see that you didn't like?

LKeithR 02-02-2019 03:20 PM

Quote:

Originally Posted by digr (Post 729787)
Just to add if you stay with threads the best case scenario the threaded collar should register on the shoulder of the ram keeping the threads out of harm way

That would be my choice too but if you look at the pic of the ram there is very little shoulder on the end of the solid shaft--that big chamfer does away with quite a bit of it. In this case I think the best bet is to bottom the tools out on the end of the threaded portion--there's a lot more area to take a 75 ton load...

milomilo 02-02-2019 03:40 PM

Quote:

Originally Posted by LKeithR (Post 729791)
That would be my choice too but if you look at the pic of the ram there is very little shoulder on the end of the solid shaft--that big chamfer does away with quite a bit of it. In this case I think the best bet is to bottom the tools out on the end of the threaded portion--there's a lot more area to take a 75 ton load...

You beat me to it.:)

greywynd 02-02-2019 05:25 PM

Quite common for threads on cylinders depending on application.

They will however, often be an extra fine thread or something like that.

If you can get the OD and pitch, chances are that we can look it up and find the actual size.

I was always having to find thread sizes at the last 9-5 for the millwrights, as we had a big mix of imperial and metric threads.


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Lu47Dan 02-02-2019 06:16 PM

I am sure, that someone around here could make an adapter from the threaded shaft to slip on or in.
Meaning, make a collar to thread on and guide the tooling to the end of the ram.
A collar with a clear bore of 1" diameter would allow you to slip the tool in, protect the threads and push on the rnd of the ram.
Dan.


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