What Did You Do Today 2025

[DalboyParticipant @dalboy]

Got around to making the studs for a couple of chucks. I got fed up with moving one set to the ER32 chuck and as I needed to make a backplate for a 5c chuck which also needed a set of studs.

 

All the studs and the partially machined backplate

Holes being drilled and tapped ready for the next stage, except I managed to break the tap in one of the holes will try to remove it tomorrow I think I have a cobalt drill bit to see if I can get it out. If not I can always move the holes around a little still leaving room for the chuck mounting bolt holes

 

[bernard towersParticipant @bernardtowers37738]

Had a go at thread milling today on my S7, what a revelation!, virtually no load on the machine and tiny chips for swarf and full depth in one pass and you can stop the thread or let it run a circular groove, magic. Only problem is you need a motorised head for the tool post and a means of running the lathe SLOW my tacho gives up below 9 rpm so slower than that. also comm cutters for 55deg dont seem to be avail(a job for another day)

[Michael GilliganParticipant @michaelgilligan61133]

Nice results, Bernard

Your motorised head for the tool post might make a good article for the magazine.

[please forgive me if that’s already been done]

MichaelG.

[JasonBModerator @jasonb]

Not heard the term “comm cutters” but 55deg threadmills are available though mosly full form.

[bernard towersParticipant @bernardtowers37738]

Its commercial cutters Jason,yes they are available but at north of £100 a pop not for me.

[JasonBModerator @jasonb]

I don’t know what tpi you are cutting but these are a fair bit less until you git to the chunky ones, I’ve used their metric ones

[DurhambuilderParticipant @durhambuilder]

Yesterday I machined the Redwing cylinder bore and bearing housings, I  forgot to take any photos at the time so these below are ‘mock ups’ showing how it was done; I did not bother recreating the clamping!
the main casting was fixed to a steel plate of appropriate thickness to bring the estimated centre of the bore to the centre of the lathe. The actual height above the machined base is not critical, a 5/8 plate brought the height to within 0.015” of the drawing dimension so that would do. I made a between centres boring bar from an off cut of 1.125” round bar with a 0.325” bit of reground hss (ex broken centre drill) as the cutting bit. This was initially too large to pass through the casting so initial cuts were done with a conventional boring bar mounted direct in the four jaw chuck. After a couple of passes I couldn’t get anymore offset in the boring bar so had to remount it in a collet block to get the required cutting radius. The between centres bar was used for the final 10 thou in a couple of passes. Final bore was 1.248” to allow for honing. Turning the casting through 90 degrees allowed me to do the bearing housings and get the same centre height. These were drilled in stages up to 1/2” then a small boring bar was mounted in the four jaw to bring them a few thou under 5/8”, the final couple of thou being taken out with a sharp reamer. For all of these operations the casting/saddle was advanced by winding the tailstock barrel against the outer edges of the bearing to keep everything square.

[bernard towersParticipant @bernardtowers37738]

Glad to see they are mock ups that looks like a screwcutting tool to me!!!

[JasonBModerator @jasonb]

They can be used to bore, it’s only the pitch that makes the difference between a feedrate and a screw thread. Not much different to using the threading insert to cut a run out groove at the end of a blind thread.

[DurhambuilderParticipant @durhambuilder]

Needs must! Yes I did bore it with a screw cutting tool, it was the only thing I had that would pass through the 1/2” drilled bore. I think I’ve used that particular tool more for small hole boring than screw cutting! With a very fine feed finish was excellent and at the end of the day it’s only the tip radius that differs, in effect I cut a 4000tpi thread in the bearing housings. I’ve  also used very small milling cutters for boring, just set one cutting edge up to cut.

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