Member postings for Chris Heapy

I tried to make some light-weight piston heads for a match target air rifle I was tuning, turning the outside and screw-cutting no problem, last job was to drill and tap an 8mm hole in the centre. No chance, the drill just heated up and that was that. Work hardened. Is it possible to anneal a titanium part that has work hardened like this?

I never tried having 10ft of stock hanging out the back of my S7B, must try that sometime (will have to drill an appropriate hole in the garage door though...)

Very true Ian, and if it's Chinese Loctite I'd best not drop it... However, it would have been a tricky job filling the bearings with grease and then assembling with Locitite in the hope of it sticking anything - or perhaps they assembled it and forced grease through afterwards (much like I had to) which is not a good way of packing bearings.

Agree with MichaelG about the Ebay seller, I have cleaned him out of my favourite filled PTFE (60% bronze-filled) but it difficult get the size(s) that you are looking for. To buy this stuff new from a stock supplier is prohibitively expensive so buying offcuts is a good solution. My need was for 2 different sizes - 30mm O.D. tube and 8-10mm rod. I managed to get some 30mm O.D. rod but of course machining that down to provide some thin 30mm O.D. seals was a criminal waste of material. But I had no choice

For the small diameter rod I cut up and turned a heavy walled section of 5" tubing, the square-ish sections thus produced provided me with nearly 2-1/2 metres of 90mm-long rods at 10.5-12.5mm diameter. Perfect, and a lot cheaper than buying that as new stock.

Edited By Chris Heapy on 23/04/2013 16:48:09

Edited By Chris Heapy on 23/04/2013 16:48:52

If there is a circlip in the rear it's hiding itself very well. I''ve even poked about with a probe and can't feel one. In the absence of any definite evidence otherwise I have to conclude it is just pressed together.

Most of those centres that fail do so because the operator fails to re-tension the tailstock during a heavy turning operation and heat expansion of the work crushes the bearings. If you can remember to keep checking, or don't clamp the chuck so tightly (let the workpiece slide into the chuck as it expands, or let the tailstock itself slide back a little) then the center will last a bit longer . You have to know your own lathe to get those settings right! However, the accuracy of even these cheap Oriental centres is better than most lathes' ability to turn parallel, a wayward 0.0005" at the tail end is not normally critical. It's a different story on a cylindrical grinder of course.

Edited By Chris Heapy on 23/04/2013 16:24:04

I believe they simply forgot to clean the swarf out before assembly so if yours is not rough to begin with then it's unlikely to develop the problem (albeit there don't appear to be any dust seals to protect it).

Yes, thanks for the memories

Rgds, Chris.

I purchased an inexpensive rotating centre from Chronos Ltd., which has replaceable bits. It's only for light duty and odd jobs not accomodated by my other centres (bit of tube work, thin parts needing a fine point etc.,). Anyway, the one that was delivered had rough bearings and Chronos quickly replaced it with no questions (cudos to them!). That left me with a faulty centre representing a challenge as to whether or not I could effect a repair of sorts. Disassembly seemed difficult, there were no visible screw threads holding it together, and a cautious prod under the arbour press suggested that, if it were a pressed together assembly, then a heck of a lot of pressure was needed to get it apart.

Instead, I tried flushing the thing through (after removing the end cap) first with engine oil, then running the thing for an hour, then refilling with moly grease using the same method. I taped a 5ml syringe on the end to force the lubricants through. The result seems to be a success, at least no more crunchy bearing - whether the bearing was damaged in the process I can't say but it seems to be OK.

I'm still curious how the thing was put together originally...

Edited By Chris Heapy on 21/04/2013 12:28:21

Edited By Chris Heapy on 21/04/2013 12:30:05

All lights in my w/s are LED now, I converted the 20w halogen flexi lamp to LED by using an AC led bulb so no other work on the psu was required. I made another bench lamp from a DC LED MR16 bulb using a length of brass tube and some turned alloy endcaps. My old Anglepoise lamp I have over the lathe was converted using an LED bayonet fitting bulb made by Philips. I have 5 other 20w equivalent LED MR16 bulbs inset in various places which used to have halogen bulbs, so overall the power savings are considerable.

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