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Thread: Repco T&C Grinder
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14th Feb 2018, 08:25 PM #16Most Valued Member
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Valve
More pics, poodah is crashing so I will keep this short
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14th Feb 2018, 11:12 PM #17.
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More neat work Shed.
Any chance on expanding on the lapping of the cylinder bore?
I know next to nothing about hydraulics so at risk of sounding dozy, how is the stroke of the ram altered?
Bob.
PS I just viewed the last bunch of photos. Outstanding stuff Shed!!Last edited by Anorak Bob; 14th Feb 2018 at 11:16 PM. Reason: Added a PS
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15th Feb 2018, 03:40 PM #18Most Valued Member
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G'day Bob, I am no expert on hydraulics either, what I did know I have forgotten so now I only know enough
to be dangerous.
Lapping the cylinder, Bob I had a pretty rough hole to deal with after boring, first I gave it a linish with emery
on a rod, then I wore out a brake cyl hone (a cheap one) and at this stage the cylinder measured about .00014"
bigger from the centre to towards one end so I thought rather than persist with cheap hones I would see how
a lapping tool would perform.
My only experience with lapping comes from 25 - 30 yrs ago lapping m/cycle
big end brgs and mains, and my old man had me lapping spool valves at some stage.
So I found this chunk of aluminum, I think that my brother poured it some time ago, I'm guessing that it would consist of
20% milk bottle tops 30% fanta and 50% coke cans.
I made a lapping tool and used valve grinding paste, 400rpm, in out in out in out.
Lots of cleaning and measuring, small adjustments on the lapping tool as you want the paste to do the work
and the lapping tool will grab if you get too ambitious.
So with every adjustment when the tool is reinserted you need to be intently listening to the gear noise/ load
on the lathe and the feel of the pressure on the saddle handwheel, the lathe that l used for this is 7hp and l
felt at the time that l really should loosen off the belts to guard against grabbing. I tried a few mixtures with
the valve grinding paste, water, trefolex paste and liquid, rocol, in the end it was mixture of all of them.
The lap broke as l was nearly finished, it fell in half when l went for another adjustment, ha... l thought
that the old coke cans would have been better than that !
I spent 6 to 7 hrs lapping and it ended up within about .0006".
cheers, shed
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15th Feb 2018, 04:28 PM #19.
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Thank you Shed for talking the time to explain the process.
Would you undertake the task again of boring and lapping or would you try to track down an existing cylinder that might suit? ( Mind you I have no idea of the cost of these things. )
Bob.
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15th Feb 2018, 08:34 PM #20Most Valued Member
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Bob I would have preferred to just buy a cylinder, or modify one to suit, or buy the tube and go from there.
But at the time I could not find anything in the size that l needed, even the tube suppliers did not have stock the
size l required and said that it would be some months before they could get it.
I had a length of 40mm 4140 so l thought that l would have a crack at it and if l stuffed it up then no big deal either try again or wait to get the tube that l wanted.
Would I do it again? yup, if I couldn't get the tube I would, I don't mind a bit of a challenge but I think that a better boring bar and a suitable hone would have saved me many hrs of work and produced a better job.
cheers, shed
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19th Feb 2018, 04:30 PM #21Most Valued Member
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remote oil filter
I had this filter with a 3/4" unf thread................
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3rd May 2018, 11:31 PM #22Most Valued Member
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More bits and the maiden voyage
Here are some work in progress pics and the bits for attaching the rod to the table.
I took about .030" off the underside of the table in an attempt at getting a flat surface for the mounting plate, things don't always go to plan though, tough as, l got the surface pretty flat with with a stone with no rock/movement in the mounting plate then sat it on some 620 loctite, nipped it up and tightened the following day.
So it had the maiden voyage today, it still has a bit of air in one side of the cylinder so it is a bit jumpy at a low feed rate, hopefully that will bleed out.
Here is a little vid of it for you guys, its just a rough set up to throw some sparks
https://www.youtube.com/watch?v=FjAR...ature=youtu.be
cheers, shed
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4th May 2018, 09:24 AM #23.
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What a job! Fantastic work John, makes me wish I knew something about hydraulics.
A couple of non hydraulic questions. Are you using the Loctite 620 as a gap filling bed for the plate? And is there a reason for grinding with the wheel skewed?
Bob.
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4th May 2018, 03:04 PM #24Most Valued Member
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Bob's Q's
G/day Bob, yes.
I couldn't get a good idea of the flatness with blue, no room to slide the mounting plate back and forth,
l could rock the plate slightly on the high spots and from this l could work out where they were.
l worked at them with a small norton stone, after l could feel no movement in the plate l measured
the remaining high spots by using an indicator on the 4 corners while trying to rock the mounting plate.
l got it sitting perfectly flat but it was obvious that it was a bit of a motorcross track down
there, so yes l wanted to spread the load over a larger surface area than a few high spots.
The surface looks worse in the picture than in reality, it felt smoother than a babys bum so
l am guessing that it was within .0005" - .001".
l used the 620 because l thought it would help me sleep better if l put it under there.
The chuck was in the way when the table was over to the right so l spun the head around for the wheel to clear
the chuck, to get full travel l need to use a collet fitted with a centre with a bolt hole and bolt in it to drive the dog,
I did say it was a rough set up
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31st Jul 2018, 01:37 PM #25Most Valued Member
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Speed control
Hi all, I wanted to slow the spindle speed for use of some larger diameter wheels that I have, they are 8" and are for my out of action surface grinder but will work nicely on this at the correct speed and the VFD will also allow for faster speeds for smaller dia wheels without having to swap the belt to the higher ratio pulleys.
I will measure the speeds at different freq's and make a chart that will stay near the grinder.
The VFD's are from ebay and cost $119 ea delivered, 380 - 380 v
2nd VFD is for controlling the speed of the work head, I have not measured the RPM but it really whizzes around and I have had to balance the job and drive dog on a couple of jobs and that can chew up time better spent elsewhere.
The VFD cubby house is just made out of 20 and 25mm angle and few pieces of flat here and there, clad it with aluminum sheet, added a couple of fans and dividers/baffles to direct most of the air from the fans through and under the VFD's and the fan in the VFD's should draw the cool air and and expel it through the vents in the doors.
I fitted a couple of Kohler air filters to the fan inlets and I might have to put a roof over them but I think I will see how they go before adding another job to the list
I dont know how hot they will get on a hot day when working so I will keep an eye (or fingers) on them and if they seem to to be getting hot I will check the air temp and if needed I will put in bigger fans, these fans are 80mm and don't seem to push much air but fingers crossed they will do the job.
I used twisted pair cable to the control switches as I found some in the shed, this apparently reduces interference from electromagnetic radiation, and I left a couple of pairs in there for possible future use.
cheers, shed
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31st Jul 2018, 01:54 PM #26.
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Neat work Shed.
You and Bob L are making me nervous about the absence of forced ventilation for the pair of VFDs I have shoehorned into the cast iron pedestal on the Hercus T and C. I need to have a hard look at it.
BT
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31st Jul 2018, 02:10 PM #27Most Valued Member
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Hi Bob, I have seen a melted one at a mates factory and I have also seen a melted one on this forum, I think that one may have been in a post by graziano? some time ago.
I would say that at the very least if you have a thermocouple put it in at the air outlet of the heat sink and see what temp you get, hot weather is your worst enemy here tho I reckon.
cheers, shed
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31st Jul 2018, 02:11 PM #28Novice
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Shed
Very nice work. It looks like it will be buttoned up soon. Great pics and progress.
Thanks for sharing
Nelson
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2nd Aug 2018, 02:52 PM #29Most Valued Member
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That's bloody nice work Shed. I really like the air filters. My poor VFD's don't get anywhere near that level of luxury!
Cheers,
SimonGirl, I don't wanna know about your mild-mannered alter ego or anything like that." I mean, you tell me you're, uh, super-mega-ultra-lightning babe? That's all right with me. I'm good. I'm good.
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3rd Aug 2018, 07:09 PM #30Most Valued Member
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