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26th Feb 2018, 05:35 PM #16Diamond Member
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One thing to keep in mind is that pneumatic feed system will use quite a bit of air. Not a problem in a factory with a large compressor and drier, but can be pretty expensive in a home shop. You will also need to dry your air supply or you will have problems with the valves. If it was my grinder i would convert it to manual feed, learn how to use it, then convert it to hydraulic feed later on.
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26th Feb 2018, 11:13 PM #17Most Valued Member
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That seems like a pretty sound plan to me. I hadn't really considered the air supply side of things.
Now I need to work out the cable drum size etc to get a reasonable traverse rate, and then make one.
Steve
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27th Feb 2018, 07:23 PM #18
Just thinking aloud here: since the table was moved - presumably successfully - by 100psi air, whould it be feasable to use 100psi OIL instead? That could be done easily with a power steering pump and maybe even air valves. THe trick is to convert the exhaust air flow back into a tank, rather than just into the - well - air...
It would be quiet, need only a small motor and not take ordinary hydraulic fittings which are rated for 3000 or 10000psi - with associated costs.
Perhaps I'm completely off, but worth at least contemplation.....
Manually grinding anything longer than 2" is a major PITA to me.... I'm looking at adding an electric feed to my old B&S surface grinder..... lots of complications compared to already having a cylinder installed and the valving to make it work.....Cheers, Joe
retired - less energy, more time to contemplate projects and more shed time....
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27th Feb 2018, 11:41 PM #19Most Valued Member
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Interesting thought Joe. I'd say you're right about the pressure side, but I'm not sure how the seals in a pneumatic cylinder would handle being constantly in oil.
I happen to have a couple of power steering pumps here too...
Dug up this handwheel from the junk at work. Its miles too heavy as is - but the bore only needs another couple of mm taken out to match the grinder shaft. Probably not much work on the lathe to remove some of the spoke thickness, and thin down the outside rim if need be.
IMG_4056 (Medium).JPG
And a photo of the decal that makes me think it was originally cable driven.
Looks like there was a hydraulic option too - I'd love to get hold of a manual that might show some detail of that but haven't come across anything yet.
IMG_4058 (Medium).JPG
I also measured the internal thread on the wheel hub that the removal puller screws into. Pretty sure its M25x1.75 thread.
Steve
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28th Feb 2018, 02:14 AM #20Most Valued Member
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Power steering pumps have a fair flow rate as they are a vane pump, so you would need a way to control/reduce that. But if you were going to go the car parts option then you might (i say might) be able to use a vane pump and a modified (bit of a cut n' shut) power steering rack? I have not had one to bits for afair while now so i can't think what needs to be done, but l think that you may be able to mod the valve to operate off a lever instead of the steering shaft. If you can get your hands on one it might be worth a look at anyway
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28th Feb 2018, 09:46 AM #21Diamond Member
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The earlier (pre HQ) power steering systems on Holdens didn't have the power steering incorporated in the steering box, they used a separate double acting cylinder to move the steering arms. I think that also applied to Falcons and Valiants of the same era.
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28th Feb 2018, 11:51 AM #22Most Valued Member
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Here's a good concise breakdown of how they work and what's inside: https://www.youtube.com/watch?v=amTnNkAhWgQ
Looks easy enough to mod, but I think the issue would be getting enough travel.
Steve
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28th Feb 2018, 12:02 PM #23Most Valued Member
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Steve I can't watch the yootoob right now as i'm on my phone.
I was thinking that you could use the streering valve to operate the cylinder that is already on the grinder, thats what i meant by a cut n shut.
Bobs idea of an early s/box is a good one, a lot of trucks had hyd assist cylinders also.
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28th Feb 2018, 12:13 PM #24Most Valued Member
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Gotcha. Thought you were meaning both the cylinder and the valve.
Steve
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28th Feb 2018, 07:30 PM #25
Looks like my blind thoughts were not that 'out of the box'. THe volume moved by the steering pump could be changed easily by changing the revs: running it clowly will move only a small volume - and vice versa. I use a steering pump that I drive with a cordless drill at variable speed to test the function of hydraulics. Works well enough without making much pressure or mess.
I would think that the seals of a pneumatic cylinder would stand up perfectly well to oil - they are meant to be oiled lightly after all...Cheers, Joe
retired - less energy, more time to contemplate projects and more shed time....
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28th Feb 2018, 09:34 PM #26Most Valued Member
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Stop poking my imagination Joe - I need to get some existing projects completed before taking on new (always more exciting) ones!!
Thinking cheap 240v variable speed corded drill from garage sale etc direct coupled to a p/steer pump (even have 2-speed gearbox to select suitable max RPM/flow).
Pressure would be very minimal - the 40mm diameter ram is ~2 sq inches area and I doubt it would take 10kg (20 lb) to move the table - so 10psi - with a bit of a pressure spike during direction change.
Steve
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28th Feb 2018, 10:54 PM #27Most Valued Member
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My guesstamation is you would likely get a stroke of about 50mm/sec on that cylinder from one of those pumps at about 30rpm,
but i spoze that you really need to pipe it up and try it to know.
From my way of thinking i wouldn't even muck around with the air cylinder and i certainly wouldn't be using air fittings on a hydraulic system even if it is operating at 50 psi, being a tight wad and cutting corners is not going to give you a reliable and practical outcome here, its a surface grinder.
good luck, shed
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1st Mar 2018, 07:08 AM #28Most Valued Member
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Why not use one of the double acting cylinders from an older car, not enough travel? You could also just re tap all the ports in the pneumatic cylinder for JIS or other hydraulic fittings. I am unsure what the automotive standard fitting is.
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1st Mar 2018, 05:49 PM #29Most Valued Member
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I've looked at photos of the HT vintage Holden ones and they look like they've only got about 300mm of travel. That ties up with a couple of posts I found on the 'net regarding guys looking for long travel rams for offroad buggies.
I'll put the hydraulic idea aside for now and concentrate on getting it going manually first. Initial step is to remove the pneumatic ram so I can pull the table off and have a good look.
The new handwheel will go in the lathe for some weight loss, and I'll mod the handle a bit so it runs in a bush or similar and spins freely rather than being solid to the handwheel.
Steve
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1st Mar 2018, 07:44 PM #30
Sounds fair enough. Keep us in the loop. Always something new to learn!
Cheers, Joe
retired - less energy, more time to contemplate projects and more shed time....
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