MG12 madness

I'm probably doing something stupid but I needs some help please.

35 year old Myford MG12 in seemingly good condition but I seem incapable of setting it to grind true. Here's what I'm doing: DTI from wheelhead to table front edge. Set table angle to give near zero change over table length, result duplicated on rear edge and top surface. (I think that excludes bent table and all slideways are clean and in good contact over entire length) Insert standard in collet. Concentricity checked. Workhead angle adjusted to give very close to zero change over 4 1/2" (Also true over wide range of speeds and no apparent lift in workhead bearings) Add tailstock, adjust until standard runs true over entire length. Result good finish but 0.009" out over 9" !!! (tailstock end is the smaller) Suggestions welcome before I go bald :-)
Reply to
Roland Craven
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I wouldn`t say you were doing anything wrong,but you seem to be trying to set it up similar to a lathe.How good is your standard?It is not a mandrel is it,i.e. tapered?Standard grinding practice is you would not hold a long part between collet/chuck and tailstock,you would run it between centres and adjust table until it grinds parallel.You would only grip short work in the collet/chuck and not use the tailstock.Again adjust table/workhead until it grinds parallel. Have you spun the mandrel between centres to check the concentricity of the centres to od? Is it the correct wheel for the type of material you`re grinding,are you using the correct work speed and wheel speed,over nine inches it`s easy to lose a bit of the wheel diameter if the settings are wrong. Sorry not to be able to give an exact reply but there are so many variables and I can understand you wanting everything clocked up apparently true but with grinding it only matters that the work finishes parallel or whatever taper you desire and the machine has adjustments to make this possible. Nice compact machine the MG12,I`ve sold a few of them. regards,Mark.

Reply to
mark

Thanks Mark and the off-group responders. Very nice machine and dirt cheap too. I'm learning. Went through it all again and found a small problem in the tailstock. Sorted so now a tiny tweak of the tailstock adjustment suffices. Ground a test between centres - my mike says round and only 0.0002" out of parallel. The finish is OK too but more playing will hopefully improve it further. BTW standard is a ground and centred parallel and measures that way too. Is there an idiots guide to cylindrical grinding? thanks again Roland

Reply to
Roland Craven

Jones & Shipman did some very good books but I`m not sure that there was a specific one for cylindrical grinding.Brown and Sharp(e) used to do some good ones too. BTW you can`t check roundness with a mike. regards,Mark.

Reply to
mark

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