Thread: Table Saw- new part

With a sharp tool, Phos. Bronze does not cut too badly. 1/2" is big enough to get a decent sized tool in and a LH thread moves away from the headstock under normal conditions.

With all that going for you, I would suggest that it would a good project to single point the thread.

Michael

Originally Posted by pipeclay

Don't know how to do the link, search RDG 1/2unc l/h.

Here you are:

https://www.rdgtools.co.uk/cgi-bin/s...2ehtml#SID=535

Frank.

Here are the links to what you are looking for on AliExpress (Bob found metric ones - presumably accidentally):
https://www.aliexpress.com/store/pro...7a855156FAaoTy
and
https://www.aliexpress.com/store/pro...16ef7c60fk0Ejl
I too have never had issues with their taps.

Michael,
Unfortunately my lathe only cuts metric threads. Something I hope to rectify someday.

Frank,
Thanks for the link. I purchased that set. AUD32 delivered. I don't mind waiting. Thanks also to pipeclay for finding them.

Joe,
I was purchasing the taps from RGD while you were posting. Thanks anyway.

Originally Posted by jack620

...Unfortunately my lathe only cuts metric threads...

There is no rule book that says you can not cut a 1/2" by 2mm pitch, although I must admit that it does seem weird/unnatural. If you wanted to feel a little less butcherous, I guess you could try for M13x2 LH. Glad to hear you have a solution, regardless.

Michael

Originally Posted by Michael G

There is no rule book that says you can not cut a 1/2" by 2mm pitch...

Sure. I thought you meant just single point the bronze nut. I'm not sure it would mate well with the 13tpi threaded screw. I suppose I could have made both in 2mm pitch, but I'm lazy.

a 2mm pitch thread over 3/4" distance will only be 0.4mm out overall. The difference between 13TPI and 2mm pitch is only 46 micron per turn. If there is any wear on the screw, it would remove some of the backlash, that's about all... and yes, it is butchery

Hi Chris,

I would just replace both the nut and screw with M12 and accept that it turns the wrong way !

You guys are killing me here! I thought you had higher standards than me.

Originally Posted by jack620

You guys are killing me here! I thought you had higher standards than me.

Hello Chris,

Don't take it too hard If you really want to go down the road of making a new screw and matching nut, then pick a common size of thread. Metric left hand is cheap and readily available. M12 LH taps as you probably know from other posts are quite cheap. That will sort out making the nut, from there single pointing a left hand thread is easy, though buying a length of LH all thread is what I would do.

I suppose what I am saying is I have more interesting things to do, whilst I can ! When easily available components are off the shelf, why not take advantage of them.

I just discovered that you can buy LH threaded allthread rod in all kinds of metric and imperial sizes by the meter off the shelf - who knew? Expensive though....

The taps turned up today, but I can't get them to cut the PB1 bronze. My little black book tells me the correct tapping drill is 10.8mm. I don't have one that size, so I drilled to 11.0mm. Despite the hole being slightly oversize I can't get the taper tap to bite. I've never run into this problem before. Taper taps usually cut very easily for me. The cutting edges of these taps don't feel sharp like the edges on my Goliath taps. Is the problem likely to be the tap, or is bronze particularly difficult to tap?

I've included some pics of my setup. I realise I should mount the tap in a collet rather than the 3 jaw, but if I do that I lose the ability to attach the crank handle. And before anyone asks; yes I am turning the handle anti-clockwise.

Ignore my previous. I managed to get the tap to cut freehand with a long handled tap wrench. It was an effort, but the job's done.
Thanks to all for the help. It's good to have my saw back.

Hi Chris,

Good work

Whilst the tap doesn't look to be the best, from that picture, some bronze can be very difficult to machine. Unless the tool is razor sharp the bronze tends to allow it to skid and rub rather than actually cut, needing a lot of pressure. Moving the work piece out of the vise a bit and then using the tail stock ram to apply pressure would have helped.

Anyway you have got a good result there.

Originally Posted by BaronJ

some bronze can be very difficult to machine.

This stuff certainty was John. I tried a few different lathe tools before I got a smooth cut. I expected it to cut just like brass, but it was more like mild steel. The swarf came off in tight curls and not shards like brass does. And lube made a big difference to the finish.