foxy99
Posted a lot
Posts: 1,457
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Does anyone know of anywhere near East Kilbride where I could turn up with a small part to be skimmed down on a lathe? I imagine it would be a 10 minute job for any guy with a lathe and I'd be happy to pay £20 (or more) for it. I'm reluctant to get out the Yellow Pages and start at Aardvark Engineering Services as you've no idea of the size of the company you're calling and often the person taking the call won't be the one doing the work. The job is to take a new motorcycle front sprocket down to the thickness of the worn original. The reason for this is a bit convoluted but here goes: - Yamaha RD250C used 525 chain and appropriately sized front and rear sprockets
- any replacement front sprockets you can buy are thicker 530 size (as used on RD400)
- there are a few OEM rear sprockets around but they are 525 size
- I want to make my new 530 front the same thickness as the original 525 one so I can use it with my new 525 rear sprocket
 replacement front sprockets for RD250C are now 530 size as opposed to the original 525 size I have new rear sprocket in 525 size 525 and 530 (now known as '50' confusingly) chains are both still available |
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Last Edit: Jan 3, 2017 15:00:38 GMT by foxy99
1974 Daimler Double-Six VDP
1965/67 Hillman Imp pick-up
1984 VW Polo breadvan
1970s Yamaha Twins (4)
1976 Honda SS50ZK1
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foxy99
Posted a lot
Posts: 1,457
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sorry for the bump but I need a man with a lathe!  |
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Last Edit: Apr 6, 2015 23:07:22 GMT by foxy99
1974 Daimler Double-Six VDP
1965/67 Hillman Imp pick-up
1984 VW Polo breadvan
1970s Yamaha Twins (4)
1976 Honda SS50ZK1
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can you not just run a 530 chain?
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That will be hardened and difficult to turn without using carbide or insert tooling, also it may flex depending on how it is held. If it does flex you will get a tapered thickness during the cut. A better option, but it would time consuming would be surface grinding, but its potentially costly as it's usually a finishing process. You could also just thin down the area where the chain runs on one side?
Of course there's also the option of softening it by annealing it first, machining, then re-hardening.
If it seems I've been unhelpful then put a wanted ad on homeworkshop.org you might find someone local with either a surface grinder or a lathe with toolpost grinder and plenty of enthusiasm/time.
Brian
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foxy99
Posted a lot
Posts: 1,457
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can you not just run a 530 chain? Hi welshpug. I will probably need to do that (as I have the 530 chain and front sprocket) but the only rear sprockets I have are 525. It would work I guess but if I could bring the front sprocket down to 525 it would be match the rear |
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1974 Daimler Double-Six VDP
1965/67 Hillman Imp pick-up
1984 VW Polo breadvan
1970s Yamaha Twins (4)
1976 Honda SS50ZK1
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foxy99
Posted a lot
Posts: 1,457
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That will be hardened and difficult to turn without using carbide or insert tooling, also it may flex depending on how it is held. If it does flex you will get a tapered thickness during the cut. A better option, but it would time consuming would be surface grinding, but its potentially costly as it's usually a finishing process. You could also just thin down the area where the chain runs on one side? Of course there's also the option of softening it by annealing it first, machining, then re-hardening. If it seems I've been unhelpful then put a wanted ad on homeworkshop.org you might find someone local with either a surface grinder or a lathe with toolpost grinder and plenty of enthusiasm/time. Brian Hi Good Scrap. Not unhelpful at all. Many thanks. Just show's that there's always more to these things than meets the eye  . I've never heard of that site homeworkshop.org. I'll go and have a look now. Thanks again  |
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Last Edit: Apr 8, 2015 12:55:02 GMT by foxy99
1974 Daimler Double-Six VDP
1965/67 Hillman Imp pick-up
1984 VW Polo breadvan
1970s Yamaha Twins (4)
1976 Honda SS50ZK1
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sal
Part of things
Mk2 Cavalier CD
Posts: 240
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What about Davey Gilmour on Cambuslang Road? I've had a few jobs done by him and been happy with his work. www.dgilmour.co.uk |
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foxy99
Posted a lot
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They look good 'no job too small'. Plus they do helicoiling and I need some of that done.
Is that the same guy who used to have a wee place in Burnside? They were really good but moved disappeared years ago
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1974 Daimler Double-Six VDP
1965/67 Hillman Imp pick-up
1984 VW Polo breadvan
1970s Yamaha Twins (4)
1976 Honda SS50ZK1
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sal
Part of things
Mk2 Cavalier CD
Posts: 240
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I'm not sure if he was in burnside previously or not.
He helicoiled two spark plug threads for me which worked a treat. Reasonable price and quick turn around time too.
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foxy99
Posted a lot
Posts: 1,457
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Jun 21, 2015 10:21:12 GMT
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That will be hardened and difficult to turn without using carbide or insert tooling, also it may flex depending on how it is held. If it does flex you will get a tapered thickness during the cut. A better option, but it would time consuming would be surface grinding, but its potentially costly as it's usually a finishing process. You could also just thin down the area where the chain runs on one side? Of course there's also the option of softening it by annealing it first, machining, then re-hardening. If it seems I've been unhelpful then put a wanted ad on homeworkshop.org you might find someone local with either a surface grinder or a lathe with toolpost grinder and plenty of enthusiasm/time. Brian Hi again Good Scrap. Just to let you know I posted on homeworkshop.org as you suggested and the first reply I got was pretty much as you say above. I've now changed the title of the thread from 'anyone with a lathe near Glasgow/EK?'to a more relevant one. Interestingly the person on the other forum advised that it would be do-able on a rear sprocket as they aren't hardened while fronts are. My question now is the viability of getting it done on a grinder. I imagine this would be expensive but are we talking hundreds or thousands? Anyone have any ideas. NB. The whole sprocket wouldn't need to be thinned. Only the circumference where the chain sits on it. So it would be coming down by approx 1/16" (1/32" on each side) over about 5mm of the radius. |
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Last Edit: Jun 21, 2015 12:11:41 GMT by foxy99
1974 Daimler Double-Six VDP
1965/67 Hillman Imp pick-up
1984 VW Polo breadvan
1970s Yamaha Twins (4)
1976 Honda SS50ZK1
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Jun 21, 2015 11:05:36 GMT
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Can it not just be bolted to a mill bed and done with that ?
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foxy99
Posted a lot
Posts: 1,457
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Jun 21, 2015 12:16:25 GMT
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Sounds good to me skylinedave, altho again I don't know much about these processes.
I know cylinder heads are skimmed (with a surface grinder ?) but they are pretty soft.
I guess the problem with my sprocket is that it's not the whole surface that needs done. The centre needs to be kept original thickness so that the nut and special washer tighten up against it properly and the spacing for the chain line remains the same
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Last Edit: Jun 21, 2015 12:17:08 GMT by foxy99
1974 Daimler Double-Six VDP
1965/67 Hillman Imp pick-up
1984 VW Polo breadvan
1970s Yamaha Twins (4)
1976 Honda SS50ZK1
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Jun 21, 2015 12:34:41 GMT
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You can do it if you have a rotary table then . Basically a table that bolts to the mill bed and you set it up for the width you want taken off . The table has a handle you turn , turning the work piece through 360 % taking off say 10mm around the edge .
It might cost you a bot more than 20 to have that done .
I would get someone to chcuk it it a lathe and just use a old tool on it . Its not going to bust if they go slow .
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foxy99
Posted a lot
Posts: 1,457
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Jun 21, 2015 13:18:22 GMT
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Thanks again. I like your answers I just had some input on another forum and a guy said (like Good Scrap) that a carbide tool would do it. Another chap suggested a vertical spindle 'Blanchard Style'. Sounds interesting I'm up for anything that works and would pay £100 or more, now that I understand it's not a simple job |
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Last Edit: Jun 21, 2015 13:19:30 GMT by foxy99
1974 Daimler Double-Six VDP
1965/67 Hillman Imp pick-up
1984 VW Polo breadvan
1970s Yamaha Twins (4)
1976 Honda SS50ZK1
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Jun 21, 2015 15:29:16 GMT
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I'd do that on a surface grinder and then add spacer washers / shims to make up any material removed from the centre.
A magnetic base would hold it in place so no need for a lathe chuck etc.
Most small engineering companies will have such a grinder.
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93fxdl
Posted a lot
Enter your message here...
Posts: 2,019
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Jun 21, 2015 17:47:54 GMT
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How about mounting the sprocket on a a spindle, made from nut, bolt and a selection of washers, then mount in a drill and when spinning either press against a bench grinder or run a angle grinder over it.
Ttfn Glenn
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Jun 21, 2015 18:49:31 GMT
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Have you tried ordering up a genuine sprocket from Yamaha, using the proper part number, it wouldn't surprise me if they are still available as nobody buys genuine c&s kits except me probably as a few times they have been significantly cheaper than pattern parts.
Unless you are doing an absolutely concourse restoration job I would just go with running a 530 chain if it doesn't cause clearance issues elsewhere.
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Jun 21, 2015 18:57:06 GMT
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Cmsnl.com have genuine 15t and 16t ones in stock
I would also guess fowlers of Bristol would be worth trying, assuming it's part number 168 1746150 or 1681746160
BTW I've attacked front sprockets with angle grinders before to make things fit, they aren't really that hard...
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Last Edit: Jun 21, 2015 18:58:51 GMT by dodgerover
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foxy99
Posted a lot
Posts: 1,457
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How about mounting the sprocket on a a spindle, made from nut, bolt and a selection of washers, then mount in a drill and when spinning either press against a bench grinder or run a angle grinder over it. Ttfn Glenn I was thinking about doing it myself. I've only lost a tenner or something if it doesn't work..... |
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1974 Daimler Double-Six VDP
1965/67 Hillman Imp pick-up
1984 VW Polo breadvan
1970s Yamaha Twins (4)
1976 Honda SS50ZK1
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foxy99
Posted a lot
Posts: 1,457
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Cmsnl.com have genuine 15t and 16t ones in stock I would also guess fowlers of Bristol would be worth trying, assuming it's part number 168 1746150 or 1681746160 BTW I've attacked front sprockets with angle grinders before to make things fit, they aren't really that hard... I'll have a look at that. The part no. is for the 250 is 1A0-174671-70 and the one for the 400 is 1A1-17461-70. Any listings I've seen supply the same for 250/400 but they are 530 so you need to find a 530 rear sprocket (although you could run 530 chain on a 525 sprocket it's not advisable afaik) but the 530 rear sprockets are for cast wheels with disc brake and my bike has the spoked wheels with drum brake. |
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Last Edit: Jun 22, 2015 2:16:32 GMT by foxy99
1974 Daimler Double-Six VDP
1965/67 Hillman Imp pick-up
1984 VW Polo breadvan
1970s Yamaha Twins (4)
1976 Honda SS50ZK1
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. I've never heard of that site homeworkshop.org. I'll go and have a look now. Thanks again 
