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: Milling table regrind|
Grinding a mill table can often do more harm than good. A bit of surface pitting won't hurt once you've stoned the surface rust off but milling or grinding it can easily make a banana of what once was a straight table.
|Thread: Am I getting an irritable old git?|
As in the dialect they might speak in New York's largest borough?
If this isn't some kind of subtle joke, it's quite funny anyway
|Thread: Is this true..?|
Good quality aluminium will hold fine threads no problem. I re-built a bike engine to allow for 3x the power via a turbo and I drilled & tapped the cases for 12mm x 1.25 pitch head bolts which is extra fine (originally M10 fine) and the main bearing bolts (from M9 fine) . They were torqued to 75lbs/ft in 2007 and that engine's still going strong today.
|Thread: Threadcutting in the lathe - help please!|
One thing that catches many novices out is that often threading a piece of stock will raise a burr which makes you think that the thread's not deep enough when in fact it's binding on the major diameter when you try the nut. You start to wonder if you've got your sums right because you've hit the full depth and the nut is nowhere near fitting so you keep taking cuts until the nut fits but then you find it's a sloppy fit and you don't know why.
Use a caliper to keep an eye on the OD after you have taken a few passes. If it's started to grow because you've pulled up a burr just carefully run over it with a flat file taking long smooth strokes as the part is turning. On a vee thread it won't take many strokes but on an acme/trapezoidal thread you might have to go at it several times to file the burr down to the correct OD.
|Thread: Which type of pin|
A 'crotch centre'.
|Thread: Does the alignment of halves of scroll lathe chuck matter?|
The negative of the L4 stamping at 8 o'clock on the right side is quite clear to see at 4 o'clock on the left. You have the orientation correct in the pic, just flip one side over on top of the other.
|Thread: gear cutters|
You don't even strictly need a button. I made my first single-point cutter by first making a fly cutter of the same diameter as a button then cutting both sides of a piece of gauge plate with the head of my mill tilted to give the form with some relief.
If you get stuck Frank I could possibly cut those gears for you, though you would have to cut any keyways required as I have yet to lay my hands on a broaching cutter set.
|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
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