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+--- Thread: Cheap and cheerful motor (/showthread.php?tid=3341)
RE: Cheap and cheerful motor - Spex - 25-09-2019
Thanks to all again. Lots of valid points. And thanks for the clearances ideas.
Lathe Vs Mills- Advantages to both.
My jig is designed for only 2 bearing A7 motors only. It allows to turn over the rod and then machine second face to same distance from centreline automatically--
Well, that is the theory, as it sets up on the big end bolt holes. They should be "aligned" with the bearing.
It will be a day or so before I can get into the workshop to do a bit more to it.
Will still listen to more ideas, even if a little wild. In the meantime I will endeavour to learn about photos on this infernal contraption.
Another question. Crack testing? As I am extremely deaf, I cannot fathom the ring when struck thing. What is a good "chemical" method?
Cheers, Peter
RE: Cheap and cheerful motor - Ian Williams - 26-09-2019
Commercial rod boring machine opperate in a similar fashion to the Lathe jig illustrated, they have several cutters on a common boring bar, once set up all rods can be roughed, finished and faced in a single operation.
RE: Cheap and cheerful motor - Bob Culver - 26-09-2019
The common jigs utilise the gudgeon in the V block for basic alignment. Assumes the rod not seriously bent.
In my expereince of Seven and Javelin cranks the ring test means little unless very fractured. (Risky applied to Phoenix as if dropped on end likely to crack the protective nitride!)
The topic of crack testing has been covered on Forum, under both cranks and steering arms. Search should find most.
Commercial firms use powerful magnets, fluid and ultra violet lamp.
Forum users report success with home kits utilisng a magnet.
Based on camparisons, I am sceptical of the penetrant only without magnet ones. Many kits have a shelf life.
Start at the rear journal and work forward , checking esp the internal radii. If OK check the oil holes. If an original crank and still OK , check method!!
Others have reported propensity of rods to crack as an extension of the gudgeeon bolt slit. Gudgeon pin fit and bolt thread important.)
Failing big ends often show a sort of spangle pattern at an early stage as sections start to lift.
RE: Cheap and cheerful motor - Ruairidh Dunford - 26-09-2019
I have this machine too but it has a an issue which I need to address, slow progress on that as the lathe jig works so well resulting in no incentive.
I think Colin uses a very similar machine.
I am very interested to hear from anyone who has successfully tinned rods for white metalling and the process they used to do it please.
RE: Cheap and cheerful motor - Dave Wortley - 26-09-2019
Peter, I have done the same scraping process as Robert. I had decent rods 0.015” undersize bores and fitted them to a new Phoenix crank. It’s a nice quiet job which I did in the early mornings over a week or so. I have a scraper made from a file by my dad many years ago which is ideal for this. They have done a few thousand miles so far without problems. It’s good to spend the time doing things like this rather than hand over cash to someone else. This is the way to learn new skills!
Cheers,
Dave.
RE: Cheap and cheerful motor - Colin Reed - 26-09-2019
(26-09-2019, 08:04 AM)Ruairidh Dunford Wrote: I have this machine too but it has a an issue which I need to address, slow progress on that as the lathe jig works so well resulting in no incentive.Hi Ruairidh,
I think Colin uses a very similar machine.
I am very interested to hear from anyone who has successfully tinned rods for white metalling and the process they used to do it please.
will PM you tomorrow regarding tinning rods and white metalling .
Cheers
Colin
NZ
RE: Cheap and cheerful motor - Ruairidh Dunford - 26-09-2019
Thank you very much Colin.
RE: Cheap and cheerful motor - Robert Leigh - 26-09-2019
Well done! I took about 2 hours each evening for four days.
Robert
RE: Cheap and cheerful motor - Ruairidh Dunford - 26-09-2019
I too enjoyed doing the rods by hand, almost zen-like, when I had no alternative.
I was discussing with Dave earlier that I latterly used an expanding reamer to start the job, then scraped and blued, this reduced the time taken considerably.
RE: Cheap and cheerful motor - Bob Culver - 26-09-2019
Hand scraping large adjustements can easily result in a tilted rod. When this topic arose previously one contributor with a large swing lathe did by clamping half way on a wood or nylon (or steel covered with paper) mandrel in chuck, then reversing, and finishing with a scraper! The fun of lathe work is the challenge of set ups.
With scraping it is very easy to start chatter marks, hard to remove.