For the machinists amongst us!

[Orcade-Ian]

Just a quick note to tell you of a workaround.  I needed to reface a very badly pitted exhaust valve from a Fairbanks Morse stationary engine - 7/16" diameter.  I didn't want to use a 3 jaw as I knew it would chatter (slightly worn jaws) but only had a 12mm 5C collet.  Slid some heat shrink sleeving on the valve stem and warmed it up to shrink it.  Fitted the collet perfectly and produced a lovely finish on the valve seat face!  The heat shrink sleeving is so thin and the collet has so much radial contact that it was a very rigid set up.

I used to be an engineer but I'm OK now!

Ian

[Laverda Dave]

That was a good workaround Ian. The lathe is the best tool I have ever bought, so useful. I used it this week to enlarge a centre hole in a 20mm stainless washer by 3mm. Turning it up in the lathe ensured it was circular and it fitted perfectly.

[Orcade-Ian]

I agree Dave,
I always had access to a lathe (well, from my early 20's anyway) and bought my first Myford in about 1978.  Later moved on to a Harrison L5 and then the Harrison 140 in the early 90's, which I still have.  I bought this one when the College I was working at closed one of the workshops and it came with a hell of a lot of stuff, including the collet attachment.  I use it almost every day!  The other thing that gets almost constant use is the Startrite bandsaw - even just making a wooden frame cradle to support the 550 while the front wheel was removed.  Those will be the last to go of all my pieces of equipment!
How else could you have enlarged that washer - apart from filing?

Ian

[Shetland Biker]

someone up in Shetland is selling a Myford laithe just now

[Orcade-Ian]

someone up in Shetland is selling a Myford laithe just now

If you are in the market for one and familiar with lathe work - or keen to learn then they are a great asset.  Unfortunately Myfords usually sell for a lot more than the larger machines - mine is still 3 phase which obviously puts most people off but I use a Transwave converter.

Ian

[Shetland Biker]

not got a clue about laithes, apart from they make things round haha,  also not got the space, or the finance to buy one haha

[Johnny4428]

Just a quick note to tell you of a workaround.  I needed to reface a very badly pitted exhaust valve from a Fairbanks Morse stationary engine - 7/16" diameter.  I didn't want to use a 3 jaw as I knew it would chatter (slightly worn jaws) but only had a 12mm 5C collet.  Slid some heat shrink sleeving on the valve stem and warmed it up to shrink it.  Fitted the collet perfectly and produced a lovely finish on the valve seat face!  The heat shrink sleeving is so thin and the collet has so much radial contact that it was a very rigid set up.

I used to be an engineer but I'm OK now!

Ian
Beginning to realise how much you are asked and do for other people Ian! You’re a victim of your own talents. Thanks very much for machining my old rusty piece of junk! O’ and thanks for the tea, again!😜

[McCabe-Thiele (Ted)]

Another skill I never learnt not helped by not being allowed to do metalwork at school.

I've well and truly missed that boat now - thank goodness for the likes of Max who used to be a member.

[AshimotoK0]

Nice one Ian,

I did a bit of that kind of thing during the 1st Covid  lock-down. I made a few adapters etc to have a go at machining down rubber rollers. My mate Graham Curtis found that on CB72/77 cam chain tensioners/idlers that the rubber appeared to be rock hard but if you remove a mm or so from the surface, the rubber underneath is still pliable. I have always shied away from using chemical softening as I reckon that may end in disaster if the roller breaks up after softening. Graham told me to use a very fast speed and really sharp cutting tool. This was a bit of a problem because I always get the guy at work to sharpen my machine tools (old school tool steel) but he was off work, being furloughed. I had a go at sharpening myself with limited success. He was correct that the underlying rubber was still pliable but I chickened out a bit as I was attempting rollers off a Black Bomber K0 cam chain tensioner assembly .... mega expensive unobtainium 2 rubber roller/one steel 'sprocket' affair.  Problem with the Bomber is that it  a very long and complicated cam-chain arrangement and I was concerned that removing 1mm or so from the diameter of the rollers might affect the geometry of everything. Then lock-down finished and I was back at work and moved onto other things. It's an interesting concept though. I wondered at the time if freezing the rubber would aid the machining. Graham has done dozens and dozens of the CB72/77 cam chain tensioners.

Has anyone else had a go at this. Only really worth it on 'unobtainium' parts though.

[Orcade-Ian]

Ash, I did a similar although not as critical job as a Bomber on my Ajax bench grinder/tool sharpener.  It has a normal grinding wheel on the left and the motor shaft at the other end drives a series of rubber rollers to reduce the speed for a wet-stone for wood chisels and the like.  Quite heavy springs keep the rollers in contact and they end up with grooves and flats which prevent the white wheel from turning.  I was able to machine the damaged surface true again with a high positive rake on the HSS tool and top speed on the lathe (1000 rpm - wish it had more). As you say, the rubber was rock hard on the surface but just right underneath.

I also now use belt dressing on the rollers - but that's of no use in your application.

Ian