JHCC

Converting an inverted hydraulic press into a light-duty forging press

Recommended Posts

I think you guys have a good handle on the bit of bow and have good workable solutions. I concur weld the frame up square and true before welding it to the table. I wouldn't trim the bottom though. I'd tack the posts where they touch the table and put shims under the gaps to prevent it pulling out of true. Say, break the flux off a stub of welding rod and if necessary flatten it till is fits tightly under the gap. Tack it heavily in a couple places before you run an arc over the shim so it doesn't melt, become part of the fill and shrink as it cools. Yes?

When you run a bead over the shim it just becomes a  part of the fill, zero effect. 

About shims in general, they're a good way to bump things true, say the posts were leaning one way, tap wedge shaped shims under the low side to bring it back to square and true. 

Frosty The Lucky.

Share this post


Link to post
Share on other sites

Now that I've got the wire welder from the college, what would you think about my tack welding the frame (just spots in the corners to hold it together in proper alignment) and then doing the full stick welding later? I'd love to see the thing together without having to juggle clamps, but I don't want to do anything that will mess up the proper welds later.

Share this post


Link to post
Share on other sites

You should ask Tom if he's going to do the demanding welding for you. Just being tacked up doesn't prevent things getting bumped out of true.

Frosty The Lucky.

Share this post


Link to post
Share on other sites

Did some welding on non-critical parts yesterday evening.

The saddle (which still needs the angle iron pieces to hold the bottom dies):

0C488324-87D1-40C3-8F1F-846FE21BC7C5.jpeg

The upper die holder (which needs a bit of grinder work):

E2F8A343-95D7-4164-B6D9-1D6CE273A061.jpeg

Feeling good about the welds:

E04F0247-8392-484C-BBE7-ADC356E6CDEF.jpeg

Next step is to clean up the ends of the saddle and drill the bolt holes through it and the bottom guide. Might make up some dies too, while I'm sorting out when Tom and I can meet up to weld up the frame. I also need to get a bigger drill bit to finish drilling the bolt holes in the top.

Still trying to figure out where to get longer tie rods for the cylinder. The manufacturer's label is missing, and the only thing stamped on the cylinder is a serial number of "0563200", which doesn't help much. I think I may have to remove a tie rod, take it to Fastenal, and see if they have a bolt of the proper size, threading, and length.

 

Share this post


Link to post
Share on other sites

Finding those long bolts may be the hardest part of the press build. Isn't there a hydraulic shop within calling visiting distance? That type and size cylinder is darned common a shop should have appropriate bolts on the shelf and know where to get specials. At least find out what grade to get.

Frosty The Lucky.

Share this post


Link to post
Share on other sites

I've called a couple of places and so far gotten some version of "We can't tell you anything without actually looking at it", which makes sense. Just have to figure out when I can get over during work hours.

Share this post


Link to post
Share on other sites

A thought occurs to me: If I can identify the specific diameter and pitch of the threading on the bottom end of the tie rod (where it screws into the end cap), can I not simply get threaded rod long enough to span that distance, assuming that the tensile strength is sufficient?

If the cylinder has an internal diameter of 4", that's a piston area of ~12.67" sq. Multiply that by the maximum pressure from the pump (4,000 psi) gives us a maximum pressure of just over 25 tons. 

I took a look at the McMaster Carr website and find they have grade 8 threaded rod with a tensile strength of 150,000 psi. The tie rods are 5/8" diameter, so their cross sectional area is 0.09765625 square inches. Multiply that by 150,000 (tensile strength) and again by 4 (number of tie rods) and you get 29.3 tons.

That should be sufficient, right?

(Also, in the Serious Irony Department, the cost for those four rods would to be more than I paid for the press in the first place!)

Share this post


Link to post
Share on other sites

Yeah, can't blame them, liability issues dealing with folks making their own hydraulic systems, especially modifying existing components. It always makes them twitchy.

We're writing at the same time again. :) 

Didn't I suggest buying grade 8 bolts long enough to fit through the table top and close cylinder, some time ago? Sure my first was to thread the table top but you pointed out the hyd. cylinder was threaded so I adapted the suggestion to feeding the bolts through the table top and cylinder to the far cap. 

This is just a correct thread pitch / Diameter x length bolt. A thread gauge is cheap and SAE, Metric combos are the norm. Criminy! I just did a quick search and it looks like they're pushing $40. and it's hard to find the simple flip out index ones that look like feeler gauge index. 

So, here's the alternative to buying a thread gauge. Pull one of the bolts and go to a Fastenal, go to the nuts bin and start trying nuts till you find one that fits. Write down the number. My memory is so shot I sometimes forget the note pad in my pocket or to look at it. Well, HECK you'll know how long the bolts you need are when you check the thread pitch so buy them. McMaster Carr is kind of expensive and the Fastenal close to me gives me a senior discount and because I'm a likable BSer they usually give me a commercial discount too. They don't even bat an eye when someone walks in with some weird contraption and heads for the bolt or nut bins. They have a LOT of useful stuff on the shelf and are happy to special order for you, only me charge shipping. I'm a likable BSer and do interesting things though. ;)

Didn't I tell you replacing those bolts would be expensive? Forget about determining the cross section area of bolts and the calculations stuff. The bolts come with a label or look it up online.

I think I also mentioned grade 8 is typical beginner overkill, EVERYBODY thinks they need grade 8. . . NOT. :rolleyes: Just look at the bolt's specs. You NEED 25 tons/ 4  is 6.25 tons per bolt, give yourself a REASONABLE safety margin, say 7 tons. The motor will burn up before you could get 28 tons.

Do NOT take my guesstimate for it but I'm thinking grade 6 will be plenty.

Frosty The Lucky.

Share this post


Link to post
Share on other sites
7 minutes ago, JHCC said:

Multiply that by 150,000 (tensile strength) and again by 4 (number of tie rods) and you get 29.3 tons.

Also of note is the fact that their next highest grade of threaded rod only has a tensile strength of 120,000 psi, and would therefore only be capable of resisting 23.4 tons of force.

Share this post


Link to post
Share on other sites

Surely not if they're running the entire length of the rod, yes? If the tensile strength is 150K psi, doesn't that take that into account?

NB: If the thread turns out to be 5/8 x 11, there are grade 8 bolts of sufficient length available from Fastenal. If it's 5/8x18, I'll have to keep looking.

Scratch that: the only grade 8 they have in that length is twice the thickness I need.

Share this post


Link to post
Share on other sites

Also, since there's no lateral load, shearing isn't an issue.

Share this post


Link to post
Share on other sites

Another thought: if I use threaded rod, I can bolt the cylinder together and not have to disassemble it to bolt it onto the top. The nuts holding the gland onto the cylinder would therefore act as spacers between the gland and the underside of the table top, thus:

89811547-EF41-493D-A06D-D8E4C7E500D7.jpeg

Share this post


Link to post
Share on other sites

John: You might want to double check the decimals there. My calc. says 0.625 dia. = 0.306 sq/in. x 4= 1.227 x 150,000 = 184078. lbs. total. / 2,000 = 92.04 tons. 

However, let's skip the rithmetic it's not necessary. This is my preferred engineering data site.   https://www.engineeringtoolbox.com/

The specifics are here. https://www.engineeringtoolbox.com/us-bolts-tensile-proof-load-d_2066.html

Note this chart is for coarse threads, compare to the same grades and dia. on the fine thread chart, down the page. 

Fine threads represent much smaller stress rises and leave more solid base stock with a stripping shear force per linear inch considerably higher than coarse. 

Being into overkill myself, I never put coarse threads in a high strength application. You're solidly in the comfort zone using anything above grade 2. Grade 5 is comfortably overkilled. Grade 8 is almost silly overkill. ;) 

I used to make stuff like this for a living you know. I make mistakes but I welcome corrections, say thank you, adopt and adapt. I won't steer you wrong, if I say it's strong enough it is. But HEAVENS YES, double check what I suggest! If I'm wrong I want to know it so I can get it right next time. Heck, I was wrong about how many grades of bolts there are, good to look this stuff up now and then. Eh?

I JUST saw your gland nut thought. NO! :o All a gland nut does is compress the packing gland it is NOT structural at all! That poor thing would be subjected to up to 25 tons of pressure and all it's designed to do is compress an oil seal against the shaft. In the old days packing was lead foil, modern packing is rope like stuff, rubber wiper seals, etc. Just enough oil is allowed to pass the seal to prevent the shaft from sticking. 

You'll rip the packing nut right out of the cylinder first time you smoosh anything heavier than a beer can, maybe then.

It's a thought though, keep it up.

Frosty The Lucky.

Share this post


Link to post
Share on other sites

Einstein used to say something like that frequently.

Richard Feynman was famous for just learning enough about a subject to know where to look things up. The quote I remember from the University librarian where he was taking advanced medicine. "Where do you find a map of a cat?"

Very interesting guy I think a lot of his eccentricities were affectations. but . . .

Is it weird to have a favorite physicist? :huh:

Ahhh, what do I care? :)

Frosty The Lucky.

Share this post


Link to post
Share on other sites

Frosty, certainly MY favorite physicist! Affectations? Maybe.......

Rober Taylor

Share this post


Link to post
Share on other sites

Well, I think Feynman's eccentricities started as affectations, he didn't want to be thought of as an academic by the regular guys so he worked very  hard at doing regular guy stuff. He talked about why he taught himself to play bongos in "Surely You're Joking Mr. Feynman!" I think by time he'd pretended to be an eccentric it was muscle memory of the brain. 

I loved the way he lived outside the box and when occasionally visiting other researcher's boxes he'd go a grand scan and ask a couple questions. Breakthroughs seemed to follow him everywhere. 

I think Einstein was such a popular and effective professor was how easily he made complex explanations relatively simple. A lot of his "famous" sayings are things he was saying often. His definition of insanity was something he said to students all the time. I really like Einstein too. 

While both these guys were interesting and eccentric characters they wren't nearly as just plain creepy weird as some of their physicist contemporaries.

Frosty The Lucky.

Share this post


Link to post
Share on other sites
2 hours ago, Frosty said:

I JUST saw your gland nut thought. NO! :o All a gland nut does is compress the packing gland it is NOT structural at all! That poor thing would be subjected to up to 25 tons of pressure and all it's designed to do is compress an oil seal against the shaft.

I'm confused. The nut that holds the gland on right now is on the end of the tie rod that holds the whole cylinder together. If we just make that somewhat longer to project through the top, how does that place more strain on the gland?

Share this post


Link to post
Share on other sites
17 minutes ago, JHCC said:

I'm confused. The nut that holds the gland on right now is on the end of the tie rod that holds the whole cylinder together. If we just make that somewhat longer to project through the top, how does that place more strain on the gland?

No, that's the cylinder cap and it's gasketed or o ring sealed. The long bolts hold the cylinder ends / caps on the cylinder. Do you have a reference for the term "Tie rod" in this usage? 

Packing Gland is a specific term. A gland is what keeps a rod or rotating shaft from leaking liquid. Some were even used to keep grease in the hub.  Wheel bearing seals are the type seal that replaced packing glands and gland nuts. Old Conestoga wagon hubs were packed with a couple winds of rope, held in place by the hub washers, the wheel nut pressed the hub and forced the packing to ride tight on the axle. 

You still see packing glands on old machinery, you had me going there. Your's probably has an O ring wiper seal but there might be something internal. 

If someone told you those bolts had packing nuts on them they were mistaken, maybe it's a foreign term or that's one weird cylinder.

Frosty The Lucky.

 

Share this post


Link to post
Share on other sites

Okay, I'm using the wrong term. Yes, we're talking about the tie rod that is screwed into the other end cap, passes through the cylinder cap, and is held in place with a nut.

BCB3D014-694B-4D38-92B9-7E0382503776.jpeg

Share this post


Link to post
Share on other sites

Once again, I'm late to the game and haven't caught up 100%

Have you mic'd the diameter of the cylinder tie rod? I happen to have a 4" bore, 24" stroke cylinder laying in the barn and the tie rod bolts mic. out at 0.59x", so not a common size. This cylinder is only a 2500 PSI cylinder though. I partially bring this up because that cylinder is left over from a log splitter project and has a bent rod, so if the tie rods will work for your project......

I will say I have zero experience with an electric/hydraulic press. With a gas powered log splitter the operation & components are the same but the priorities are completely different. Seed is #1, wedge design #2, and power third so flow rates and working pressure are the opposites......I have a spare 2hp motor and a few spare cylinders in the barn, now my wheels are turning

Share this post


Link to post
Share on other sites

The problem is that the longest 9/16-18 bolt that Fastenal carries (as an expanded catalog item, which I assume means that it needs to be special ordered) is 14" long, just baaaaarely long enough to hold the whole thing together (from the top of the cylinder cap to the bottom of the base is 12-3/8" + 1/4" spacer to accommodate that little hump where the hose connects + 1-1/4" for the top = 13-7/8"). At $19.59 each, that's not cheap.(Grade 5, for what it's worth.)

On the other hand, I can get two 3' lengths of 9/16-18 threaded rod (60,000 psi or 7.5 tons per bolt) from Gamut for $8.65 each. Even with the nuts, that's all four fasteners for about the cost of one bolt. Would this work?

7 minutes ago, Fowllife said:

Have you mic'd the diameter of the cylinder tie rod?

I have not, but I measured it very carefully with calipers and a good ruler. I'm confident that it's 9/16-18, but I'm still going to do Frosty's trick with taking one bolt off and toting that to Fastenal to find the matching nut.

Share this post


Link to post
Share on other sites

9/16" would more then likely be what mine is also. All the talk of 5/8" above just made me bring it up.

I don't deal with tensile strength much, more just shear, so I'll let someone else more qualified answer that one. If it were mine I would run with it for this application and just watch for stretch.

Share this post


Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.