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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: Metric ML10 lead screw threadform
25/04/2018 10:05:37
Posted by not done it yet on 25/04/2018 09:30:22:

ACME is TPI and metric trapezoidal is pitch and never the twain shall meet - or at least they shouldn’t!

True that, but then my Denford lathe had a cross slide screw that was 1/2" OD x 2.5mm pitch. They just used the same material and cut a 2.5mm thread in place of 10tpi. Weird things happen.

25/04/2018 09:30:04

Pretty easy to get the angle with a gear tooth caliper and some basic trig. I guess I'll grind a 30 degree tool in preparation and check the original screw when it gets here.

25/04/2018 08:52:57

It's certainly 3mm pitch.

 Assuming the screws were made in house, they could easily have used the same tooling for both.

That's what concerns me, or rather that they might have used a 8tpi insert and set the lead to 3mm.

 

 

Edited By Pete Rimmer on 25/04/2018 08:53:27

25/04/2018 07:09:43

I thought the same thing about them all being 8tpi because of the ML7 being so but the screw is certainly 3mm pitch. It's confirmed on the lathes page that they did make metric ones.

I can't think why they would make a metric pitch screw with ACME form but you just never know.

24/04/2018 20:01:14

Evening!

Does anyone know if the metric lead screw for the ML10 is trapezoidal thread or ACME? OD is 16mm with 3mm pitch but I don't know the form or if it's full form or stub form.

If someone had a factory print that would make my day!

Pete.

Thread: Silver soldering contradiction
12/04/2018 23:30:48

In my work we have a guy that re-tips drill bits with silver solder. There's a spring clamp that presses the tips hard against the drill to solder them. These things see extreme duty and they are soldered with no gap.

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

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