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Thread: Orden TC grinder
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10th December 2013, 10:16 PM #31Distracted Member
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My answer to that is no it's not the same, and a quick thought experiment will demonstrate that.
Also how have you checked the spindle centres to see if they are running true
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11th December 2013, 05:56 AM #32SENIOR MEMBER
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Hi pipeclay,
using centres in the lathe is the same as using Bench Centres.
You spin the actual shaft by hand nothing else.
Phil
Precision-Inspection-Bench-Centres.jpg
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11th December 2013, 06:45 AM #33Philomath in training
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Gee Phil - you should know better than to post pictures like that!
First you will have Stuart thinking that he needs one for his indicator collection, then he'll tell us of all the wonderful things he's done on it so a few of the rest of us will decide we have to make one and then...
Michael
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11th December 2013, 07:01 AM #34Philomath in training
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Bryan - an overnight thought. Have you checked various places along the shaft? The shaft is chunky and I wondered rather than it being bent whether it has been bad from new. To manufacture a shaft like that the method is probably rough it out on a lathe and then grind the ends so if it was not set up properly it may be that you have vibration just from an eccentric mass. The fix for that could be a skim of the centre section. Bent I'd expect to see a point of maximum TIR but if eccentric there should be the same TIR in several places.
Michael
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11th December 2013, 11:32 AM #35SENIOR MEMBER
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I haven't got the time to think about it too closely, but it seems to me that all you've demonstrated is, that there is runout on the bearing area WRT the centres. That does not *necessarily* demonstrate that there is runout WRT any other area. It's indicative but not definitive. The centres could be out.
I think you need to mount up 3 gauges, 4 would be better, one on each of the machined bearing areas and one on each of the tapered areas. See what runout patterns you observe. Or clock each area separately and record the results on the shaft with a fine tipped pentel pen etc.
PITA doing this sort of stuff - I just spent time tweaking my Chipmaster to turn parallel between centres and got it down to 0.0002" over 5" which was as good as I could manage. I did machine the HS centre in position before I did anything else.
PDW
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11th December 2013, 02:10 PM #36
Hi Brian,
I think here are two things, one is runout, the other is balance.
Even if the taper run out relative to the bearing location is zero, there could be runout elsewhere causing vibration.
If it turns out that it is a bent shaft, what next?
Try and straighten it?
Machine a new one from scratch?
Find someone with a cylindrical grinder?
I'm going to suggest that you ignore it... and re-assemble the head, then with the thing running, figure out a way of holding a TPG or similar, or maybe some other existing attachment, and regrind the taper in-situ with the spindle running.
Regards
Ray
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11th December 2013, 10:17 PM #37Distracted Member
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Ray, I like your thinking. Actually that was the first thing that occurred to me, some kind of in-situ truing, but I decided I wanted to know what was going on in there.
Michael, Peter, I did clock it at both tapers and both bearing registers and the error was greatest at one of the registers: .035mm. The amount and location (o'clock) of error was consistent at each place after repeated tests. So I'm convinced the shaft is bent. Attempts to straighten it with my little press were completely futile.
In short, I assembled it and it's now showing .05mm TIR at the wheel arbor. That's about half what I got previously. Why I don't know. Maybe I goofed. Maybe there was an assembly problem. Anyway what matters is, how much runout can be tolerated? Given that the wheels are not a tight fit on the arbors, and that they get trued anyway. I don't have a wheel yet but I powered it bare and vibration was negligible. If it vibrates too much with a wheel I will consider ways of truing the taper as Ray suggested.
To put the project in perspective, all I want to do at this stage is single point tools and maybe drill bits. Super finishes are not required. And start to learn a bit about grinding. If I can achieve those things for minimal cost I'll be happy. And just for the record, I knew this machine was a roughie when I bought it, I'm happy with it, and its condition is no reflection whatsoever on Harty.
BTW, where do you guys buy your wheels (online)?
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11th December 2013, 10:31 PM #38
What size wheels are they Bryan?
I get norton Surface Grinder wheels (12" x 1" x 3") from my local place, anywhere that stocks norton should be able to get them.
the only online place i know of is AbTec in the UK Abtec4Abrasives / Sanding / Grinding / Polishing
Cheers,
Ew1915 17"x50" LeBlond heavy duty Lathe, 24" Queen city shaper, 1970's G Vernier FV.3.TO Universal Mill, 1958 Blohm HFS 6 surface grinder, 1942 Rivett 715 Lathe, 14"x40" Antrac Lathe, Startrite H225 Bandsaw, 1949 Hercus Camelback Drill press, 1947 Holbrook C10 Lathe.
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11th December 2013, 10:39 PM #39
Bryan (and Ewan),
you may or may not recall that I have a few 12x3x1 and 12x3x3/4 grinder wheels 'surplus'.
Let me know if you can use them.Cheers,
Joe
9"thicknesser/planer, 12" bench saw, 2Hp Dusty, 5/8" Drill press, 10" Makita drop saw, 2Hp Makita outer, the usual power tools and carpentry hand tools...
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11th December 2013, 10:52 PM #40Distracted Member
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Thanks Joe, but I want a cup wheel, 125mm as far as I can tell.
The only online source in Aus I know of is https://www.bolt.com.au/straight-cup...1007_1008.html
Postage I think was about a $13 minimum a year or two back. Guess that's ok.
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11th December 2013, 11:07 PM #41
Hi Bryan,
I've picked up a few CBN wheels on ebay, a bit mixed, but there are bargains if you are patient, if you want to buy on-line then travers have a pretty good range Flaring Cup Grinding Wheels | Travers.com
I've bought wheels from Australian Industrial Abrasives they don't sell much on-line, the hardest part is figuring out what the best solution is for whatever you are grinding, for general use, white alox is a good starting point.
Regards
Ray
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11th December 2013, 11:21 PM #42GOLD MEMBER
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Hi Bryan,
Do you have more than one wheel arbor?
Stuart
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12th December 2013, 12:16 AM #431915 17"x50" LeBlond heavy duty Lathe, 24" Queen city shaper, 1970's G Vernier FV.3.TO Universal Mill, 1958 Blohm HFS 6 surface grinder, 1942 Rivett 715 Lathe, 14"x40" Antrac Lathe, Startrite H225 Bandsaw, 1949 Hercus Camelback Drill press, 1947 Holbrook C10 Lathe.
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12th December 2013, 01:02 AM #44GOLD MEMBER
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If you're going to be changing wheels on the arbor and not arbors on the shaft. I can't see your runout being an issue.... though I've been wrong before. Though I'd say it will be an issue if you end up with multiple arbors with diamond/CBN wheels.(based a sample of one lol)
Well if arent going to machine it is one setting the that will help, but if you are, it doesnt matter where the HS center is(though it sure will help if you have to remachine it at a later date)
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12th December 2013, 06:16 AM #45Distracted Member
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Ray, yes white alox will be my starting point. I forgot I actually have a thin flaring CBN wheel I got from an ebay seller in eastern Europe a while back. Seems very fine and may be good for finishing and touch ups, but alox will be needed for shaping (should have mentioned I don't use carbide tooling). I recall looking for surface speeds for CBN and not really finding any. Is it supposed to run faster than alox? Also I'm thinking since you can't true it AKAIK, your setup would need to be good. That's why I couldn't get it to work on a bench grinder.
Stu, I only have one arbor at this point, but hope to make some more.
Ewan, Harty said he couldn't ID the taper. It's nominally 1" x 3/4" x 1" long.
Finding one or two would sure save me some hassle.
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