building a hydraulic cylinder

idacal · Jul 11, 2015

I purchased an all terrain forklift at an auction I knew it had hydraulic issues but I didn't realize how bad they where I just figured seals and repacks. oops

one lift cylinder and the one tilt cylinder are shot they have bends in the barrels from something hitting them hard . I have always wanted to build my own cylinder figured this is a great one to try. material was 550.00 for 78" of 4" barrel and 78" of 2.5 rod I have extra for mess ups. my overall length needs to about 68" okay thats the background I chucked it up and everything was going okay but I have a difficult time holding the wires for measuring threads and I cut my threads way to loose the piston and nut have way to much play. I could redo the whole end or cut the threaded portion down to 3/4 thread. its on the single acting cylinder advice would be appreciated. also my threads seem very rough Im using a carbide insert tool with a positive rake insert
there will be welding later on I promise

123weld · Jul 11, 2015

well, if you redo them, you can use hss ground to 60 degree. instead of using the crossfeed, i'd set the compound rest to 29 degrees, and use it to feed in, that way, 97% of your cutting is on the front of your bit, less resistance that way - nicer finish. I also turn lathe on, run a wire brush over threads before laying wires on. carbides finishes are sometimes affected by going to slow. hss gives a friendly finish at low rpms, and use a thick cutting oil.

jpump5 · Jul 11, 2015

Never tried it but boss/ toolmaker suggested using grease to hold wires in place when measuring threads.i just used mating part as gage,after getting close.

X2 on compound set to 29 degrees ,HSS tool

zapster · Jul 11, 2015

I never use wires to thread measurements...

I turn the major diameter first and then the minor diameter on the end for about 1/8" from the end..
Start threading and when you get close to the minor diameter start trying to get the nut to go on...
If it don't only take .002 at a time until the nut starts then use a fine file to take the roughness off the top of the thread and then keep trying the nut until you get results.

Sometimes you have to keep threading but only take .001 at a time and keep the thread burr clean until success.

I do these all the time.
It's a real fine line between it fits and now it's too loose...

...zap!

zapster · Jul 11, 2015

And FWIW most threads like you are making are about .060 DEEP and thats a good starting point.

...zap!

idacal · Jul 11, 2015

Thank you zapster that would be way easier never thought of turning the minor diameter. I Have a dificult time hand grinding the hhs to cut threads with. i meed to sit down and watch you tubes of it until it makes sense. Last time I tried threading with a hhs I got almost to the last pass and broke the tip that was a booger picking it back upalso a sloppy thread

123weld · Jul 11, 2015

your trying to hard, or thinking about it to much, is all. i used to take my bit to the side of the bench grinders wheel, and shoot for a 12 degree relief on both sides ( keeping it cool in cup of water), by ****ing the bit back 12 degree while doing so, will give you the the 12 degree at the nose automatically. use the 60 degree notch in your fishtail/center guage, as a template for shaping your bit. you can afford to lightly put a decent sized radius on the tip, being its 3/4 or 7/8 threads. a pointy tip can't disperse heat well and is weak. that may be what went wrong when you used hss

labparamour · Jul 11, 2015

zapster said:
I turn the major diameter first and then the minor diameter on the end for about 1/8" from the end

...zap!

Thanks, Zap
I love that method...I'm gonna try and remember that!!

Idacal,
If you have extra length on the stock now might be the time to try recutting the threads w HSS using Zap's method and getting a better fit. I suppose being single acting cylinder, turning down to 3/4" might not be a problem, either...

DB

12345678910 · Jul 11, 2015

it's already been said I think

Once you make a pass, don't go full length, just do a quarter inch- stop and try the nut on.

That way you won't go too small and if you do it's only in the chamfer area.

Get some $5 scrap and practice the part before you do the $500 material.

zapster · Jul 11, 2015

For grinding your own threading Tool you need a "Arrowhead"....
Starrett makes them and you grind and match the profile for the tool.

Very handy if you don't have a thread grinding jig....

...zap!

Oxford · Jul 12, 2015

Fwiw, when I was in school for machine shop (a long time ago) we took the hss blank and only ground 1 side of it to the correct angle not both sides so it was at a point. By doing this you could utilize a factory edge and only have to worry about grinding one side correctly. The teacher also had us put layout fluid on the top and scribe out the angle for a guide when grinding. You then use the gauge when you stat to get close.

bent · Jul 12, 2015

Lots of ways to hold thread wires.

One is to put them on opposite ends of a piece of tape. For your project, take a piece of duct tape about 3" long. Lay one thread wire on 1 end, lengthwise with the tape, overlapping the tape by about 1/2". On the other end put the other two wires, spaced about one pitch diameter apart. Cover with another piece of tape so all the sticky disappears. Sometimes it helps to add a piece of thin plastic between the layers of tape to stiffen it slightly. Now you can easily hold all three wires with one hand, while manipulating the mic with the other.

Another way is a small piece of cardboard. Punch the wires through both sides about the right distances apart.

Always clean the chip pan before using thread wires or other loose measurement pieces like Jo blocks. You never drop wires in a clean chip pan.

Get a "fish tail" gage. It has the 60 degree included angles for checking your hand ground tools. It also has marks with divisions of an inch like 14, 20, 24, and 32 so you can check the pitch you are threading. (you do take a pass at .002 depth to scribe the part to double check gearbox settings, don't you?) It also has double depth of thread for various pitches so you don't have to look up thread data in a handbook for threads that will never be checked or audited. Also remember if you are infeeding on a 29 1/2 degree angle to add 15% to the depth of thread to compensate for the cosine error of the infeed angle.

OPUS FERRO · Jul 12, 2015

idacal

Where is the lithium grease on the steady-rest?

zapster

Is an 'Arrowhead' and a 'Fish Tail' the same thing?

Opus

idacal · Jul 12, 2015

thank you for all the advice opus I used the steady rest to get the rod centered drilled I used 2 dial indicators one on top and one at the side mounted in the tool post then I backed it down Im not sure if that is correct but thats what I did, that quick it was starting to mark the chroming to the point I could feel roughness with a fingernail and I had way oil on it but the steady rest had been broke and fixed some time in its past and the rollers are not quite square. I do have a fish tail and have ground bits before but I shake something horrible and that makes it difficult I will grind a bit for the redo if takes an hour I will get it figured out, I finally took the time to sharpen a 5/8s drill bit and by the time i had it figured out and the bit would drill I had 45 minutes in it Im sure I will get it just takes me a while.
Bent thank you on those methods of holding the wires when I was turning the backing plate for the 3 jaw chuck in the lathe I would spend as much time holding the wires and fishing them out of the chip pan as I spent cutting the thread I will remember that number 15% I ran a shallow cut and checked with a thread gauge then took two passes at .020 thousands each turning 60 rpm then started trying to clean up the mess :dizzy: next time way slower

forhire · Jul 12, 2015

idacal said:
Thank you zapster that would be way easier never thought of turning the minor diameter. I Have a dificult time hand grinding the hhs to cut threads with. i meed to sit down and watch you tubes of it until it makes sense. Last time I tried threading with a hhs I got almost to the last pass and broke the tip that was a booger picking it back upalso a sloppy thread

Zapster uses a Clark grinding jig and after reading his thread I bought one on ebay for myself. I really like how well it can do cutters for acme thread also.
http://weldingweb.com/showthread.php?354081-Lets-Thread-Some-316-Stainless!!!!&p=3654331#post3654331

Before I bought the jig, I'd rough them out on the bench grinder and then finish them on the belt sander. If you have a belt or disk sander with a tilting bed it's easy. I free handed with my portable for a lot of years.

123weld · Jul 12, 2015

you can stop the steady rest from scoring your part by : take a piece of emery cloth, put oil on the back side. wrap the emery cloth almost all the way around the shaft w/ the back side against the shaft in the opposite direction your parts going to turn. take the end of the cloth and lay it on the mating surface of where the upper and lower bodies come together, and tighten the nut down. then seat the three rollers/feet against the emery cloth as you would against the bare shaft. You can kick the lathe on for 10 minutes at 500 rpms, and nothing will heat up to speak of, the emery cloth will stay in tack 100%, and it wont score your part as you described was happening.

OPUS FERRO · Jul 12, 2015

forhire

Well this answers that ['Arrowhead' / 'Fish Tail'] . . .

http://weldingweb.com/showthread.php...31#post3654331

zapster - your a victim of forhire's Time Zone advantage.

Opus

bent · Jul 12, 2015

If your steady rest is marking your part, I would stop right now. Make a thin wall sleeve to be a press fit on the shaft, say .0005 to .002. Heat the sleeve and slide on to the shaft to the desired location for your steady rest. When you are finished, reheat the sleeve and slide it off. You have far to much money in that shaft to risk making a groove that will ruin your seals.

I have never used the emery paper trick on a roller steady.

Another hint for steady rests: Cut a circle of cardboard a little larger than the hole in your steady. Cut a couple of cross slits in the center slightly larger than your shaft. Slide the cardboard on the shaft up to the steady rest. This helps keep the occasional wayward chip away from the fingers and helps reduce rolling chips into your part.

If the thread is undersize, I would make a special mating nut rather than turn the entire thread down to the next standard size. Even though it is a one way cylinder, that threaded end already looks undersize to the shaft.

snowbird · Jul 12, 2015

bent said:
If your steady rest is marking your part, I would stop right now. Make a thin wall sleeve to be a press fit on the shaft, say .0005 to .002.

Machining that thin would take me a week

I like the emery cloth trick thank-you 123weld.:drinkup:

Could it be possible if the treaded end is now too small to cut it off, drill and tap the shaft then use a proper grade and size bolt ?

Idacal, thank-you for this post, very informative inputs here to absorb/digest.:drinkup:

bent · Jul 12, 2015

No, say 1/16 to 1/8" wall. .0005 to .002 press fit.

There are many cylinder rods with the piston secured by a hex head cap screw.

building a hydraulic cylinder

idacal

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