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: How to maximise material removal rate on a mini lathe?|
1. Get a decent piece of HSS
2. Grind a RH roughing tool with a ridiculously steep top rake and generous front relief.
3. Watch it slice off material like butter on your low powered lathe.
|Thread: Source of good HSS lathe tool blanks|
I make 'one shot' tangential style holder from small nubs of stellite. I mill a notch in some hot rolled steel and braze the stellite on the end tangential style. They get sharpened by grinding the top face.
Did you know that if you get a new piece of Deloro Stellite it will have a tiny notch ground in one edge on the end. The notch is to tell you that the tool is strongest if you grind it with the notch on the top.
|Thread: Morse taper spec.|
I've yet to hear and tales of woe of anyone getting Jarno tapers wedged in such a fashion, and they are all made the same angle of taper.
|Thread: Paint for Colchester Lathe|
What constitutes a 'good' brush? I've always run away from any kind of painting job partly because I find it tedious and partly because I always seem to struggle to get any kind of a good result. It could be that I have never tried to paint with a good quality brush.
You can get decent results with roller and brush. It's how this was painted:
Edited By Pete Rimmer on 21/05/2018 07:28:25
|Thread: Myford Super 7 VFD Controls & Clutch Switch|
What is the microswitch for Nick? An electrical interlock for the belt lever?
|Thread: Metric ML10 lead screw threadform|
If you hand-grind a threading tool to within the half-degree difference between acme and trapezoidal flank angles you're some kind of superhuman. It's only half a thou difference at the tip of the thread at the pitch we're discussing.
I just found a NOS set of half-nuts on eBay and the thread is quite roughly cast into the metal (zamak, possibly) half-nut. I guess that makes the half a degree half-angle difference immaterial.
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.
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.
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
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.
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!
|Thread: Silver soldering contradiction|
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|
You can only get argoshield light on the hobby deal, not heavy.
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|
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|
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|
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.|
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
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