Member postings for Pete Rimmer

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.

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

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

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.

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.

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.

That's real customer service

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.

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.

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.

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.

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

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.

If your lathe is supposed to use a 120/127 combination for the metric-imperial transposer then you can susbtitute this for 34/36 and the result is very close indeed - less than half a thou over an inch of thread.

So for a 6mm pitch screw:

6*36/34=6.35294 x4 /25.4= 1.00046"

You'd be hard-pressed to cut a thread that accurate.

It was a 600x400 from Insize.

No, we didn't measure it before mounting on 3 pads. The repeat-o-meter was a great tool for checking the flatness of plates and the only one which tested truly flat was the brand new one. All the others checked has some small amount of variation (but they still produced fairly consistent scraping prints).

As far as 'setting it on the points it was ground on'. You're never going to know how it was held, so even if that were a verified true statement it makes for a futile debate.

One of the guys brought a brand new in the box plate to the recent scraping class. We set it on three points at 1/4-1/5 spacings and checked it with an autocollimator/repeat-o-meter, and it was as close to perfect as you could measure in the home shop. Not even a tenth variation.

I bought some cheap cork tea coasters and glued them to the bottom of my plate. Thee coasters 25% in from each respective edge. Two at one end and one at the other.

I don't know where you're located but there's a nice Shaublin cabinet still advertised here. I bet it would make a grand base for a ML7.

https://www.homeworkshop.org.uk/index.php?option=com_adsmanager&view=show_ad&adid=31683&catid=2

Edited By Pete Rimmer on 16/01/2018 20:18:01

I use it quite often. It has a very dark pigment which means it's easier to see when it's rolled out thin. I'd use it all the time except for the fact that it's oil-based and doesn't come out of your skin too easily.

Sandik scrapers are gash. One of the guys at the class brought a brand new one, tried one of mine and put his Sandvik insert in it for the rest of the week.