Member postings for Pete Rimmer

The video is a demonstration of a tool for winding vaping coils for kanthal wire for those e-cigarette things. Seems like it could be re-purposed for winding coil-springs but it might not be man enough to coil spring wire.

I find that stainless can pull up a nasty burr. A quick swipe with a file gets it gone though.

Maybe they are not originals, but replacements. Replacement jaws from PB come with a note that they might need work to ease the fit as they are machined 'tight' to allow for wear in the chuck.

I've done this too. Turned a flat disc and pressed it in to a dome shape. You need to get the OD of the blank just the right diameter and I had several tried to get one right. It's far easier to form a shallow dome and turn the OD on the lathe.

I have replaced several, never found a glass one they have all been plastic. Just buy a welding mask protector screen for pennies off eBay. Turn a shallow dome in some scrap material, heat up the plastic screen until it goes soft then pull it over the dome to make a dish of it then trim it to your required diameter.

I would say yes, but before you condemn the previous builder, understand that you don't know the circumstances. They might have been well-intentioned but incompetent, lack skill or mechanical sympathy or there might be other reasons why the work is poor. My father was trying to complete a Jinty whilst he was on heavy meds for the cancer which eventually killed him. The quality of work was shocking but it wasn't because he was not a capable engineer - after all, he did a lot of work to renovate a 1:1 scale Jinty years before.

I couldn't bear to scrap it so I donated that part-built frame and all the bits to the The Gravesend Model Marine and Engineering Society with the understanding that it would need to be re-worked from the start.

I'd call that a sliding dog.

I read both of those David, but the only thing between not knowing and knowing is learning. Many a hurdle has been crossed with the aid of a simple explaination how.

Ketil (and Nick),

If you have access to another lathe do the following:

Get a tube of micrometer blue (or other engineer's blue)

Bore a piece of stock so that it will pass over the thread and the OD register. This is a test-piece to get the taper angle set on your compound.

Make a template from card or take measurements to get the approximate angle of the taper from the threaded part. Use it to set the compound angle on the lathe.

Now cut the taper in the piece you bored.

Blue up the taper you cut and use it to take a print off the taper by pressing it lightly and giving a bit of a turn. Removing and replacing the test piece in a 3-jaw will not affect your results at this oint and there's no need to dial it in, just re-cut the taper each time.

Adjust the compound angle until you get a good print on the spindle from the piece you cut and then keep the compound set to that angle. Keep that tool in the toolholder so the tool height is preserved because adjusting the height even slightly will change the angle.

Now get your backplate blank, face, bore and thread it for the spindle all in one setup then cut the taper on it. Everything will now be concentric and you can finish off facing and turning the OD with it mounted in the Mikron. that will ensure the best mounting face for your chuck.

Edited By Pete Rimmer on 30/10/2018 13:44:31

Yes that's exactly the idea. It was a one-off setup for cutting one particular internal taper angle in a hardened shaft using PCD tooling.

Love that cross-slide idea.

Oh yeah there are a dozen ways to do it. Just use whichever suits you best.

I think it's quite difficult to make any taper that fits another without a test-fit and some blue. I use a tenth-reading dial to make small top-slide adjustments and I've even seen a setup that someone made that used a pair of jacking screws to set and then hold a taper angle for very fine work.

Re-setting the tailstock is a simple matter just put a piece of scrap in the chuck and turn it to the diameter of the tailstock barrel. Now bring the tailstock barrel up to it, mount an indicator on the carriage somewhere and sweep across from the barrel to the part you turned. Adjust until they read the same.

Ah, it was more of a response to George. He asked why no scale - it would be of very limited use.

No scale is going to be good enough if the taper you're cutting has to fit into any other taper. For that, you need a sine bar or an indicator and some trig. Or a lot of trial and error.

Can you not modify it to fit Kevin?

I think that's for grinding punch press/fly press tooling because of the short table travel. We had something similar when I worked in a sheet metalworks back in 1986.

The belt guard you need. Is it the pear-drop shaped one with long slots in it? I have one of those off a ML7, if it will fit.

I think the answer probably lies with that off-set square drive fitting in the cone pulley. Have you figured out it's purpose Bill?

Edited By Pete Rimmer on 24/10/2018 11:23:27