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Member postings for Pete Rimmer

Here is a list of all the postings Pete Rimmer has made in our forums. Click on a thread name to jump to the thread.

Thread: Exploding Grinding Wheel
30/06/2020 00:40:21
Posted by andrew lyner on 29/06/2020 23:59:23:

I religiously stand to one side when I turn on my bench grinder and I see other people do the same on YouTube. I wonder how dangerous those things actually are, though.

I only heard of one specific case of a grinding wheel exploding and it was pretty horrific. A relative of mine had to rebuild a guys face - which was seriously damaged.

I am always pretty careful about using my wheel and would never hit is or push hard against it but what about the issue of using the side? The drill sharpening jig I bought seems to work only when mounted so as to tough the side of the wheel so what about the 'only on the front ' mantra that you seem to hear pretty regularly.

A higher apparent risk is with angle grinder discs which have various words of warning on them. But, on YouTube again, you see all sorts of antics used by some of the DIY 'performers'.

I never actually had a proper course on grinding and I know they are given to all professional too users. Is the risk real or is it just the fear of litigation that makes managers so careful about grinding? I am at least as careful as the next man (not the one with only one eye).

Bench/surface grinder wheels are safe enough so long as you take precautions when handling and mounting. Ring test, blotters, dressing etc. If they run out of true or over-speed then you increase the risk of bursting them so always observe the printed rpm limit. standing to one side is good practice but I only do it religiously after mounting a new wheel - just in case I cracked it when clamping.

You're unlikely to overload your bench grinder to the point of stressing the wheel. Your typical 6-8" bench grinder is what 250-330 watts? A surface grinder with a 8" wheel will be 0,75kw - three times as powerful - and they slow down on heavy cuts. You would have stalled the bench grinder by the time the surface grinder had slowed appreciably. Similarly, surface grinders and tool & cutter grinder can grind on the side of the wheel. You can do the same with your bench grinder just go easy - many have spring-loaded rotors. What you don't want to do is dress the wheel too thin or with too great an undercut.

Angle grinder wheels in comparison are very safe. They are reinforced and will take significant damage before they let go. You still need to respect them and they can still harm you if you lose a chunk from jamming or if the centre pops out but the damage is usually more evident before they'll let go and they do so in a much less catastrophic way.

Thread: Inherited Lathes and Milling Machines
28/06/2020 22:52:59
Posted by not done it yet on 28/06/2020 22:06:36:

2 used chuck backplates - one original and one likely in steel - just made over £100 pounds each on ebay. Amazing prices for just a screwed backplate!

Raglan backplates, not common, square thread and both handy sizes. You could understand the NOS one going for that amount but the other one did very well for what it was.

28/06/2020 17:52:36

Hi Shaun,

Sorry to hear about your father. I had to do the same when my dad died 10yrs ago. A difficult time.

As for moving advice - much depends on the size of the machinery, the location and most importantly the access. If you can manage to give some idea about the above - perhaps some pictures - then advice will follow I'm sure. Your location would help too, it could be that there are some used machinery dealers local who could offer you a job-lot clearance service.

Advice I will give right away:

Small items have value too, especially if they are good quality. Many people will sell a machine and every tool that goes with it, not realising that often the tooling is worth more than the machine.

Get valuation advice from more than one source. Right here is a good place.

Workshop clearance specialists - proper ones - will get rid of everything for little hassle but also offer the least - they have overheads and need to make a profit plus they'll have to dispose of the 'rubbish'. Back-street ones will offer little more and might leave you the mess to clear up.

A very small amount of cleaning will increase the interest significantly. No-one wants to pay good money for a dirty, rusty, neglected machine covered in junk.

Pete.

Thread: Inserted cross slide feed nuts
28/06/2020 15:38:55
Posted by Andy Carlson on 27/06/2020 00:03:23:

@David: thanks - good to see someone who has actually done it. I was thinking along similar lines. Making one tap seems less hassle than making three.

Did you screw cut a square thread or a pointy one?

Looks like you heat treated your tap - did you just harden it or did you harden and temper?

12.5 TPI... an interesting idea thanks but I probably lack the gears to do that. The Faircut has 2 off 20T and then goes up in 5T steps to 65T. I suspect this is the full original set. It would also mean making the screw and nut at the same time.

FYI the Faircut has a permanently engaged leadscrew..

Cutting a feed screw length thread brings some additional challenges that I'd rather save until another occasion.

For now I'm going to go with 12 TPI and see if I can actually make a nut that works. At least the gearing is straightforward.

Andy, if there's a particular gear you need for your setup to get you 12.5TPI I could probably make it for you.

Thread: Myford MG9 grinder
26/06/2020 17:57:06
Posted by Chris Evans 6 on 26/06/2020 07:56:06:

Pete, I have not forgotten you. I said I would ask a mate if he had a manual but with covid and me having a stroke just have not got to see him yet. I am recovering well and will ask as soon as I can. Chris.

Thanks Chris, I appreciate that.

Steven, do you have the broken bits for that handwheel?

25/06/2020 18:27:36

Hi Steve,

Well done on finding a grinder. I hope we can compare notes because the manual seems to be unobtanium.

So far my progress is that I have the cabinet and main casting all painted then I decided to assemble the machine and see how well it operates before going any further. So it's all together with the wheelhead and workhead still in the light grey paint and I've done some grinding with it which has produced very nice results. I was most worried about the wheelhead bearings which turned out to be in great condition going by how smoothly and quielty it runs.

All of the ways need scraping but not really desperately so I'll be doing those when I strip it for painting again. I just need to get hold of a 32" dovetail straight edge. I also have to think carefully about how I'm going to support the table for scraping since it will certainly bend under it's own weight.

Can I ask does your machine have the original motor and does it mount on the four bolts on the rear of the casting? Also does yours have any sort of cover on the tail end of the wheelhead? Also what arrangement do you have for the coolant pump? I'd sure like to see some pics if you can post them.

Pete.

Thread: Inserted cross slide feed nuts
23/06/2020 20:49:46

Posted by Andy Carlson on 23/06/2020 18:28:24:

The lack of concentricity on the cross slide insert suggests it may be threaded but getting anything to turn it will take some thinking. The compound insert doesn't show such noticeable eccentricity.

If the hole is blind I'd pump it full of grease and wind the screw into it. If it's a through-hole I'd wind the screw right in then punch it out with an aluminium drift against the end of the screw.

Thread: Material for a Chuck Backplate
18/06/2020 19:16:53

All those high-speed steel CNC chucks don't seem to suffer from ringing.

Thread: rescuing a chuck
18/06/2020 18:51:03
Posted by Bazyle on 06/06/2020 11:34:32:

Why are you talking about reduced capacity? you surely do not intend to use the jaws with only the last partial tooth gripping the scroll.

If you lose one tooth your capacity is effectively reduced by 1 pitch, if you have a minimum number of teeth that you need engaged in order to not break any more.

Thread: Material for a Chuck Backplate
18/06/2020 06:29:05

Steel is perfectly fine for making a backplate. The ringing is a common-repeated non-issue. When I skim my cast iron clutch pressure plate it rings like crazy but t doesn't happen in the bike. Same goes for backplates.

Low-cost chucks are cast iron because the bodies are cast to their gross shape which minimises machining and material costs. Same goes for backplates - anyone anywhere could cast them. If you took the time and cost factor out of the equation they would be made from cast steel or machined from solid.

Thread: J&S 540 belt keeps coming off
14/06/2020 19:12:05

Mine had a plain leather belt and ran just fine. It was just about the only past of it that didn't give me trouble :D

Thread: Make-shift surface grinding of a threading die face
14/06/2020 14:49:19

If I was compelled to attempt something like that, I would turn up a make-shift shallow die holder with a spigot to hold it in my battery drill. Mount the die in the holder, cobble up a rest and spin it in the drill whilst pressing it against the wheel of my bench grinder.

Thread: Wooden Gears
14/06/2020 13:54:41

Ironwood laugh

Thread: Brush motor repair
14/06/2020 11:49:31

Never mind, you gave it a try and that's what matters.

FWIW I tried to repair a Metabo commutator which metred out just fine electrically but also had the ring of fire arcing problem. It was heavily worn but looked ok. Field coils were fine. I checked and cleaned between the segments very carefully and there was no sign of any bridging but I never did find the reason.

A new rotor cured it.

Thread: J&S 540 belt keeps coming off
14/06/2020 10:58:49

On my (very old) J&S grinder the motor was also rubber mounted. If those rubbers are perished or gone squidgy then the motor shaft won't be parallel to the spindle shaft and that can cause the belt to wander off the crown.

Thread: Interpreting these bearing blue patterns
14/06/2020 10:55:28

The lump needs removing for sure. It will be causing a false reading on the entire remainder of the bearing.

14/06/2020 08:26:51

The shiny bands are where oil is not remaining between the surfaces so you're not getting proper lubrication. You'll need to scrape those lightly, but imagine that you are scraping the divots in a golf ball - don't join them up.

The dimple in pic 5 is a result of the above - the spindle has picked up the bearing slightly. You'll need to scrape that little island down before you can get a sensible print. It doesn't matter if you crate a divot, just don't have that lump there or leave at atol when you've scraped it.

What blue are you using? Looks like it's got bits in it.

Thread: Drilling HSS
14/06/2020 08:09:15

I drilled one with a broken carbide end mill. I just ground a small spade end on it and pushed it through in the drill press.

Thread: Chipmaster vfd
13/06/2020 18:38:18

Those variators should have an adjustment for the cones. Yours might only need adjusting.

Thread: Smart and Brown Sabel
12/06/2020 06:01:17
Posted by Jim Beagley on 11/06/2020 21:57:05:e.

Lastly, anyone know of a source for the oiler felt? Mine has definitely seen better days. Lots of the oil ways were pretty blocked, so I think this strip down was worth the trouble - mind you, I've not finished yet.

 

Oh, and I still cannot budge those stupid hammer-in rivets. Bah.

 

Jim, you'll find the felts for the Southbend 9" lathe will fit it. Loads of those available.

Hammer-drive rivets I lift using old feeler gauges to get them unseated at first.

Edited By Pete Rimmer on 12/06/2020 06:05:48

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