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

[Frosty]

I thought I recalled John saying they were 5/8"so that's what I was going by. Yes, measure them carefully and adjust grade to suit.

YOU guys keep calling those long darned bolts, "Tie rods" so I went searching so we could get the terminology straight. Item 20 on the parts diagram order list. 

https://www.colemanequip.com/parts/model/Case-310B-Forklift-Parts/No-Description-vg/D24080-HYDRAULIC-CYLINDER-0mRH/

You're right the end caps are held on with Tie rods.

You might look through the site for your cylinder, this one is 3" x 6",  they might have longer tie rods for not so much.

I sure as heck would NOT use all thread. I'd special order bolts long enough or buy 9/16" stress proof round and thread it myself first. I'd change it back to mounting with the pin Anything but all thread.

If you do use all thread paint it with gloss enamel. If the all thread starts to stretch the paint will peal and give you some warning. 

Frosty The Lucky.

[JHCC]

Sounds like I should keep trying to find replacement tie rods. Strange that so many other parts are readily available, but not those. 

[Irondragon Forge ClayWorks]

I agree with Frosty about threading stress proof rod, less chance of it stretching.

[pnut]

9 hours ago, Frosty said:

Richard Feynman was famous for just learning enough about a subject to know where to look things up.

 

9 hours ago, Frosty said:

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

He admitted as much in the PBS documentary The greatest mind since Einstein. I'm paraphrasing but he said his donors wanted a mad scientist with wild hair so that's what I gave them.      He's also one of my favorite physicists.

Pnut

[Fowllife]

There are many different types of threaded rod rod that can be used in a lot of different applications. Many contractors use them along with epoxy for anchor bolts for large metal building. Those would typically be slightly larger with larger reaction forces, but stretch or breaking at the threads is extremely rare. 

I mentioned the cylinder I had laying around because it is basically junk. If they tie rods spec the same you could cut them down and re-thread for your application.....but then what is stronger, threaded rod, or your new cut threads?

[JHCC]

 

1 hour ago, Fowllife said:

There are many different types of threaded rod rod that can be used in a lot of different applications. 

 Exactly: we’re not necessarily talking about your run-of-the-mill hardware store all-thread. For example, McMaster Carr has a 9/16-18 threaded rod in a “medium strength steel” (grade B7) with a tensile strength of 120,000 psi. Even if you subtract the depth of the threads (I’m guessing about 1/32”) from the radius, that still leaves about 0.196” sq. in cross-sectional area, which would be a 11.78 tons per corner. Is that really going to stretch that much? The McMaster Carr website says that their B7 threaded rods “are often used to secure pressure tanks, valves, and flanges” — isn’t that similar to what we’re talking about here?

[Fowllife]

Man I hate going down a rabbit hole. This talk of threaded rod vs stress proof bolts got my mind a spinning.

So, the pump is 3000 psi operating, 4000 psi max. What is the cylinder rated for? In a quick search all of the tie rod style cylinders I see are rated for 2500 or 3000 psi, some with a max surge pressure of 4000 psi but most don't list anything other then operating pressure. All the 4000 psi cylinders I see are fully welded.

Hoses are another question also. If it was not used to it's full potential in it's previous life it might not have 4000 psi hose on it.

I bring all of this up because what are we truly designing to? 18 ton @ 3000 psi, or 24 ton at 4000 psi? Or maybe even less if the cylinder will bypass a seal above 2500 psi. These number change the safety factor for the cylinder tie rods.

As I have mentioned, I'm not a fluid dynamics expert. I'm just asking questions, partially to educate myself.

[JHCC]

The manufacturer's label is missing from the cylinder, but considering that I'm not changing anything mechanical (that is, we're looking at the original motor, pump, hoses, valve, and cylinder as built), I'm pretty confident that this is going to be okay. It ran just fine before I started disassembly, although I do admit that I did not run it under load.

On 6/19/2019 at 6:47 PM, Frosty said:

On 6/19/2019 at 2:33 PM, JHCC said:

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?

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.

In a PM, Tom said he thought this would be fine, but suggested that I do any tack welds in the middle of the seams. That way, he will still be able to do proper welds in the corners, without having to weld over spot welds at critical points in the joints. Which makes perfect sense.

[Fowllife]

I understand completely. I was just pointing out that with a system with somewhat unknown components we are making assumption on max theoretical forces. If the unlabeled cylinder happens to be lower pressure the forces are much smaller and you safety factor on the tie rods is greater. 

[JHCC]

Understood.

Still, it's interesting to note that over its original working life, the cylinder bent its mounting pin rather considerably and bowed the 1-1/4" thick table up by a fat quarter inch without suffering any damage itself.

[JHCC]

Another detail: according to some additional research, the yield strength (that is, the minimum stress under which a material deforms permanently) of a B7 grade bolt is 105,000 psi, compared to 92,000 for a grade 5.

[JHCC]

2 hours ago, JHCC said:

Is that really going to stretch that much?

Well, to answer my own question, the Engineer's Toolbox gave me the formula for bolt stretching according to Hook's Law. Plugging in the numbers for load, nominal diameter, pitch, length of bolt, and Young's Modulus, I get an elongation under load of 0.0287" and a tensile stress of 61,582 psi. That would exceed the yield strength of hardware store all-thread, but is well within that of grade B7. Look good?

2 hours ago, Fowllife said:

I'm just asking questions, partially to educate myself.

Same here. This whole process is a fascinating exploration of all kinds of interesting subjects -- and we haven't even gotten to forging yet!

[JHCC]

Spot welded the frame together:

Slight gap (R) where one of my business cards will be permanently entombed:

(As a point of interest, the tops of the posts are the original ends of the channel as they came from the rolling mill, hence the distortion.)

Adding a couple of braces to the sides to help keep the spacing right:

The bottom guide and the saddle fit, but tightly. Got some fettling to do. 

 Very happy with how this has gone. Everything is nice and square, and the gap on the outside of the feet is no more than ~1/32”. 

[Frosty]

When looking for the correct name of Tie rods I looked at a lot of spec sheets for tie rod cylinders. There are a number of psi ratings, the to you're talking about are the working 3,000 psi and the max 4,000 psi. sometimes called shock loading pressure. 

The pressure you are actually worrying about is neither of those but the "Proof" pressure. Proofing is the pressure below which the cylinder will NOT fail, it is not the working nor max pressure, it's the point you don't want to exceed. ever.

It's the same principle as proofing a gun barrel. We proof things at silly high stresses, far above what any sane individual would consider. 

Relax, the cylinder will NOT fail with that pump and motor. 

Have you looked at the available parts lists of the sites I posted? Parker sells and ships. Aggressive Hydraulics seems to have a lot of cylinders. Both list 5" x 10" and 3" x 10" tie rod cylinders in the 3,000 - 4,000 psi range. I didn't price the tie rods but wasn't sure what dia. your cylinder takes. 

John. Stop figuring bolt strength from the psi rating of the steel. Go straight to the bolt charts and avoid the chance of dropping a decimal. It's much easier and safer to let THEM do the calculations and do the proofs in the tensile test machines. 

Frosty The Lucky.

[JHCC]

6 hours ago, Frosty said:

Have you looked at the available parts lists of the sites I posted?

Maybe I’m looking at the wrong places, but I can’t find replacement tie rods listed anywhere. Lots of tie rod cylinders, but no tie rods on their own. 

[Les L]

JHCC,

Do you have a pipe fitting supplier in your area? Style 40 dresser couplings for large diameter pipe use bolts like you are looking for, they are b7 if I remember correctly. 18" style 40 uses 5/8 x 22 bolts.

[JHCC]

I think I need to stop looking for replacement tie rods for hydraulic cylinders specifically and broaden the search. I found a supplier of tie rod assemblies (with turnbuckles and the like) that might be a possibility. Further research in progress.

[Dasher]

JHCC, once again, I'm butting in, sorry, but if you have posted the diameter of the existing bolts, I've missed it, and for some reason, this site will not load previous pages of threads, so , if I go to bed for a few hours and try to look at a previous thread, unless it is in new activity, or still on an unfilled page, I miss it, [ most likely I am doing something wrong, lol], anyway, for your rods, bolts, I would be inclined to just get the highest grade available, bottoming out at 8..8, or whatever is equitable in your area, also, at the risk of creating a bit of an arguement, High Strength allthread is available in grades 8.8 and above, and is possibly  suitable for your purpose, the issue with allthread is very much the fact that is not readily identifiable, and looks just like commercial grade thread, I have done many, many projects that have been subject to heavy loadings, often with just chemical epoxy anchor in concrete, as someone mentioned on Friday, myself, I would look for marked bolts in preference, but H.S allthread is not a killer.

[JHCC]

1 minute ago, Dasher said:

for some reason, this site will not load previous pages of threads

This is a known issue with the forum software. What you need to do is click on "next", "previous", or the page that you want and then refresh the page. It's annoying, but it works.

3 minutes ago, Dasher said:

if you have posted the diameter of the existing bolts, I've missed it

I need to confirm, but it looks like an imperial size of 9/16" diameter x 18 threads per inch.

[Dasher]

Imperial or metric is probably irrelevant, but I'd just be looking for the highest grade 9/16" unf or 14 x 1.5 mm pitch bolts, the 1.5 might be hard to find in your area, so I'd look for the 9/16 mm bolts, obviously I've missed the reason why the existing bolts are unsuitable, so I might be leading you astray.

[Frosty]

I specified Tie rods in the search terms (Yahoo) Prince shows a number of tie rod cylinder parts lists though I didn't look for prices, might take a phone call for specifics. http://www.princehyd.com/portals/0/cylinders/3000psiTieRodParts.pdf

There are a number of others as well.

Frosty The Lucky.

[JHCC]

I’ve called a couple of places, and the only thing I have learned for certain is that I need to confirm precisely what I need (rod diameter, length, and thread spec) before anyone can give me a good answer. 

On a totally different subject, I’ve finished fettling the saddle and bottom guide, and they both slide beautifully. I need to drill holes for the pair of bolts that will hold those two pieces together. Since they won’t be under any significant load (just the force it takes to pull the guide back down between squishes), how big do we think they should be?

[Frosty]

You can tell them the tie rod's: diameter, length, and thread pitch, can't you? The current tierod length pluss the table thickness plus the spacers necessary to compensate for the bow, plus nut thickness & lock washers and 3 threads above the nuts. My concern was they'd only sell a part for a given tie rod piston. They can't tell you much without knowing what you need, they don't read minds.

I'd probably use 3/8" bolts for the bottom die saddle, they won't be under any stress but they do need to squeeze the saddle and the gussets you welded in make it a lot more rigid. On the other hand it's not a high speed tool so perhaps it only needs a set screw / bolt to keep it from going walkabout. 

Frosty The Lucky.

[JHCC]

Sounds good. It’s a pretty tight fit already, so I’m not so concerned with squeezage. 

[JHCC]

21 minutes ago, Frosty said:

You can tell them the tie rod's: diameter, length, and thread pitch, can't you? 

Still need to confirm the diameter and pitch, but I just pulled one of the tie rods from the cylinder to take with me. There’s an ag implement place up the road that may be able to help.