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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: Argon gas
08/04/2018 17:57:28

You can only get argoshield light on the hobby deal, not heavy.

08/04/2018 09:20:24

If you are using it for your hobby then BOC do a deal which is a lot cheaper than list. Current hobby price for argoshield size y is £47/yr rental and £35.71 fill with 79p surcharge. Plus Vat.

If you're a very light user and mean to keep the bottle for a long time then a rent-free would be better.

Thread: Trying to find some D1-3 back plates
01/04/2018 12:42:30

I've made a couple from steel and also from barbell weights but the weights tend to be too thin so the pin threads poke through. You also have to be careful with the locking screw hole because at first glance they appear to be on the same PCD as the stud holes but they are not. For my own use I tend not to even bother with locking pins I just drill and tap for the studs, screw them in and use it.

As for the taper I tend to make it snug. It's almost as shallow as a Morse taper and you can see those visibly move when you set a taper in your tailstock with a soft drift even after setting itin by hand, so there's more tolerance than you might think. A loose fit of course is intolerable for the camlock taper.

Thread: Correcting an off bored cylinder
23/03/2018 06:38:48

Is the hole in your chuck bigger than the cylinder hole? If so, turn and bore a piece of round or flat stock that plugs into the centre register of the chuck and superglue in in place on the flat end of the cylinder. Now use that plate to locate the cylinder centrally on the chuck, hold it tight against the chuck face using the tailstock ram and and snug up the four jaws with the soft packing until you have it held for boring.

Thread: Does 4 jaw chuck quality matter
19/03/2018 22:46:30

Not only does quality matter but suitability does too. I have a couple of Burnerd lightweight 4-jaws and whilst you can't question the pedigree of the chuck you do have to be careful how much you tighten the jaws or it's easy to put a deflection in the chuck face. I guess that's why they made them with such small screws and chuck key.

Thread: Lathe chuck not true.
02/03/2018 18:24:17

Grinding the jaws should only be a last resort IMHO and only after careful checks have been made. If you think about it, jaws are hardened steel and a very compact and strong shape. Chuck face is essentially a flat disc of cast iron with three slots milled in it. If something's going to go out of shape when abused it's more likely to be the soft iron chuck not the hard steel jaws.

I had a 4 5" PB chuck with severe runout that varied between 8-15 thou and I suspected the jaws until I put them into another similar PB chuck and they were perfectly fine. Turns out the slots in the front face of the chuck were dished and it was holding the jaws bell-mouthed, probably from being abused by over-clamping something held at the extremities of the jaws.

Consider also the commonly accepted statement that grinding the jaws is only good for the diameter they are ground at. That is exactly what you would expect if the chucks jaw guides were dished or domed.

Edited By Pete Rimmer on 02/03/2018 18:24:30

Edited By Pete Rimmer on 02/03/2018 18:25:01

Thread: Diamond grinding wheels
01/03/2018 00:56:22

I use diamond for stellite, usually I use it for grinding threading tools as it holds an edge so well. You can get it sharp enough that you have to handle it with care. Doesn't seem to bother the diamond, once again if used at slow rpm. Bit hard to find stellite now though.

28/02/2018 19:37:43

You can use diamond wheels to put an edge on HSS all day long so long as you turn the wheel slowly enough and even better if you use a little coolant. Electroplated diamond products have an initially aggressive cut but settle down to their 'normal' cutting rate quite quickly and stay there a long time so long as you don't overheat them.

Once worn beyond their normal usable life they can still be used to put a very fine honed edge on something but the material removal rate will be minimal.

Thread: Problem with Little John Mk2
25/02/2018 09:00:37

If you run the test cut again with a larger diameter part and you're still getting a taper then take a look at this video done by a friend of mine a year ago. He doesn't mention how or if you can adjust the spindle angle but I could ask him for you if it turns out you're turning a taper due to a mis-aligned headstock. Many lathes can be adjusted on the clamp bolts:

https://youtu.be/OfjVroJxs9U

 

Edited By Pete Rimmer on 25/02/2018 09:03:20

25/02/2018 08:49:04

What diameter was the part you've done your testing with Steve? It might be nothing more than the brass bar is bending away from the cutting tool but as you get closer the chuck the spring in the part is less so it's forced to cut deeper.

Run your test again with something of fairly large diameter but not too long - say 1.5" diameter with only 3" sticking out the chuck. Take a light surface cut and see what result you get.

Edited By Pete Rimmer on 25/02/2018 08:49:58

Thread: Couple of things at Lidl
19/02/2018 20:52:38
Posted by Clive Foster on 18/02/2018 18:24:36:

Pete

6" disks would require a totally impractical amount of re-working. Effectively you'd need to cut it right back to the motor assembly and start over. Including making your own tool rest / work table. Might as well start with a bare motor and be done with it.

The carrier disk fitted is quite thin, a touch under 5 mm, with a similar space behind it so there is limited room between the edge of the tool rest / work table and body for a proper grinding wheel or diamond lap disk. Boss appears to be around 35 mm diameter as eyeballed from underneath with the table removed.

I'm going to try it out as is with the paper disks supplied and, if that seems OK, get some finer ones.

Its only rated for 15 minutes use at a time before you have to stop and let it cool down. Its never going to be up to proper TipLap or similar tool standard but should do just fine as the second stage in a three step sharpening process viz :-

1) basic shaped of the periphery of the bench grinder.

2) clean up hollow ground surface left by bench grinder to have small lands "top & bottom" at desired angles.

3) hand finish to bright, sharp, edge with diamond lap or stone.

Clive.

Ok thanks for the review Clive. It 's a shame that 6" discs won't fit but there's always 4" discs, which will still do the job just that you'd have to be a little careful not to run off the edge.

The 15min duty is no problem lapping a carbide scraper usually takes more like 15 seconds.

Thread: Colchester Bantam 2000
18/02/2018 21:48:04
Posted by needleworks on 18/02/2018 20:07:34:
Posted by Mick B1 on 18/02/2018 19:08:48:

.559" is 3 1/2 thou down from 9/16. My guess is imperial.

I thought of 9/16, but I can't find a left hand acme tap 9/16 x 10 tpi anywhere on the net

You won't and it probably wouldn't help you anyway. IIRC the Bantam cross slide screw is a 2-start thread. .100" pitch but 5tpi lead.

Thread: Couple of things at Lidl
18/02/2018 17:26:32
Posted by Clive Foster on 08/02/2018 13:34:48:

Picked up the 5" \ 125 mm disk sander this morning for £ 30. Parkside PTSG 140 B2.

Figured that it would make a nice basis for a Tiplap style tool grinder after up-gunning the tool rest and arranging a proper grinding wheel in place of the standard plain disk intended for self adhesive abrasives.

Checking it out was pleased to find that it runs up nice & smooth. Even more pleased to see that the standard tool rest is decently robust for an all plastic device. Probably only needs some positive stops on the tilt adjustment and some fixed angle guides for the table to ensure same grinding angle every time. Comes with two each of 80, 150 and 240 grit self adhesive disks. Quick noodle on t'net shows that grits down to 400 are readily available so maybe it will do fine as is.

A round-tu-it project right now but we shall see in due course.

Clive

I had suggested trying out this as a cheapo carbide scraper grinder. Trouble is, the most common size of diamond flat lap disc is 6". Do you think a 6" disc might fit with adaptions? If not, it would be restricted to 4" discs but they would still do the job.

Thread: Parvalux motors - highly recommended.
08/02/2018 20:52:11

That's real customer service thumbs up

Thread: ML7 motor - Tyco Crompton - wiring/burnt out?
06/02/2018 20:34:36

Could be that old favourite - swarf in the gubbins. Worth pulling the end bell off just to check for that. My first lathe gave a little lightning show because I didn't at the time realise the importance of keeping the swarf out of the vents.

Thread: ML7 restoration project
05/02/2018 19:12:24

Well done Matt, you got that for a great price

Since you are a raw novice to machines and machine work it might be worth mentioning your location. You never know, you might have a seasoned machinist/forum member right on your doorstep who would be willing to cast their eye over your machine and offer up some sage advice in person.

Thread: New Granite Surface Plate
21/01/2018 20:48:26

Thanks Michael I will add that to my book collection. I find lots of great texts on archive.org - far more than I'll ever have time to read but sometimes I do refer to them.

21/01/2018 19:16:10
Posted by Michael Gilligan on 21/01/2018 18:52:29:
Posted by Pete Rimmer on 21/01/2018 18:23:57:

Everything bends, it's how much that matters. Where we're talking about here is not something that's enough to matter.

.

Pete,

It's not enough to matter to you ... that's fine.

It may, or may not, matter to me ... that's for me to judge.

It certainly matters to the people who make AA grade surface plates.

MichaelG.

I won't argue with that. Everyone knows what their own standards are. For some the theoretical problem problem of standing a plate on the airy points is far greater than the practical one.

21/01/2018 18:23:57

Everything bends, it's how much that matters. Where we're talking about here is not something that's enough to matter.

Thread: Harrison 155 imperial thread cutting
21/01/2018 18:08:04
Posted by Jon on 21/01/2018 17:05:09:

Think you would be even harder pressed to get hold of a 34 and 36 tooth change wheel not to mention the size difference between a 120 to 34 and 127 to 36, may not mesh with the other gears needed about 16 to 18" away!

The 127 and 120 are compounded so the actual diameter difference is 9.21-2.57=6.64 inches. You might need an idler in the cluster but you could choose any appropriate diameter for that. I haven't studied the Harrison gear cluster.

It's an option anyway.

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