Mount the stock rod into a VEE block and place on a truly flat surface longer than the rod, that will allow you scribe at each end at the same height with both marks on the same axis. If you then turn the assembly through 90 degrees and adjust your height marking gear (vernier or other) to centre height you can mark the centre at each end, adjust to the 2nd dimension you need to centre pop and mark the rod end.

Emgee

Another typo edited.

Edited By Emgee on 30/11/2016 13:42:16

Edited By Emgee on 30/11/2016 13:47:42

If you have a vertical slide that can also be used. Clamp the bar to the vertical slide and indicate the end true to lathe axis, centre drill shaft hole and then use vertical siide for crank pin hole. Leave work clamped to vertical slide but turn it 180degrees so other end is now facing the headstock and repeat drilling. This can be more accurate depending on your marking and punching abilities.

Hi Paul

You will need to add a couple of packing pieces (parallels) each side of the clamp for the Vee block to sit on when turning the assembly through 90 degrees.

Emgee

I don't think I would do it the way the instructions suggest because when finished it needs to be parallel to the shafts that will be turned later.

So I'd centre drill each end of the bar stock on centre and then skim the od true between centres. These centres will be needed when the shafts at each end are turned.

Then mount that true in a 4 jaw and offset the bar by what ever amount is needed. You'll need to tap it parallel to the bed on 2 axis but if your 4 jaw is any good that shouldn't be a problem. The offset can be measured with a dti using the cross slide calibration to actually measure it. Strictly speaking DTI's aren't measuring instruments. You'd need 2 DTI's one to check the top is parallel and another to check the side and the offset.

Then turn the what ever the engine people call it. Then machine the shafts between centres. Some people add something to stiffen up the weak spot formed by the offset part. Maybe loctite or super glue a short length of bar in.

I believe one if the intentions of these was to turn cranks on a face plate. If well made there will only be a need to measure the offset,

**LINK**

I'd still do the initial centre drill each end and skim between centres. That way the accuracy of the above can be checked as well. If your lathe turns a taper or what ever include that in the check. Might be your best option and at this price scarcely worth thinking about castings and making one.

John

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