was wondering what the most accurate way of measuring bolt hole spacing would be, without the use of a cmm machine. i am sorting out s2000 engine mounts and want to draw it up on cad but i need to hole spacing to be accurate

I don't know about the accuracy "per se" but depending if the bolt holes were on the same plane couldn't you measure from the edge of the bolt hole 1 to the same edge of bolt hole 2. Then you would just have to offset for the radius of the bolt itself to find your center points....

Very rudimentary and probably impossible to do correctly, but its what popped into my mind.

Beags

the above is one of methods I have used on the past sometimes making up a paper gasket and measuring that, another is to to make up some studs with pointed ends and screw them into the holes and measure between the points.

If you're making engine mounts and the holes are on the same plane, surely you can measure edge to edge of holes and increase the clearance on the bolt holes?

Are you after the angular positions from one to the other? Stick a bolt in each hole and wrap a string line round the plain shanks, then you can locate them with pitch and angle

How accurately can you machine the holes once you've measured them so accurately?

I worked mine out but placing a bit of paper over the holes and gently rubbing a pencil over the surface (just like a child would do in play school! ) , Then I used the paper to mark the holes through onto a bit of plate with a centre punch but you may possibly be able to scan it and then use that as a reference? Not sure if thats possible as I have just given away my secret that my car is being built with skills I learnt when I was 4!

P.S. Feel free to make fun of me, I was thinking about making the dash out of paper mache and the clocks out of pasta stuck on with PVA glue!

The scanning sounds like a good idea actually. Wonder if I could transfer it to cad some how

quote:

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Originally posted by SeanStone
The scanning sounds like a good idea actually. Wonder if I could transfer it to cad some how

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Going to try and scan it in tomorrow, import to solidworks and see what happens!

Yep, rubbing and scanning has worked for me - although by the time you've messed about scanning, scaling importing you might aswell physically draw some reference axes (a couple of base lines) on your rubbing and measure the rubbings and draw in CAD from those.

Then print 1:1, cut out and check against the block, adjust as necessary

[Edited on 20/5/11 by FASTdan]

[Edited on 20/5/11 by FASTdan]

with a set of verniers you should be able to get the centres between 2 bolt to the nearest 0.5mm atleast

measure the distance from each hole to every other hole in the group - when you go to draw it in cad it should have all the correct positions and angles
(the tricky bit is drawing it, some cad packages are easier than others)

[Edited on 20/5/2011 by mcerd1]

With a decent vernier you can easily measure bolt hole spacings to within 0.1mm providing you use the right method.

1 Measure the distance between the far edges of the two holes.

2 Measure the diameters of the two holes

3 Take measurement 1 and subtract half the diameter (or the radius if you prefer) of each hole.

Simple and effective

HTH

Mike

To find the distance between two holes of equal diameter using a vernier.
Measure internal size of one hole. Whilst vernier is still inside the hole press the ZERO or RESET button.
Now measure between the two holes using the same internal jaws, ie. between the outer edges of the holes.
Reading will show required dimension.

Have you not got the OEM engine mount?

Surely you could just draw round that and through the bolt holes to get a paper template for the new mounting plate....?

You coud even use the OEM mount as a drill jig to get the holes perfectly aligned.

If you haven't got the OEM mount somone else might have one and be able to do it for you (IIRC daniel mason is building and S2000 engined car).

[Edited on 20/5/11 by nick205]

i do have the oem mount yes but i want to design it and play about with it on cad and then add centre punch dots for the template i print out.

You could just scan the oem mount. Simple

With any luck the original designer would have selected some round number of mm as a pitch, so it should come out nicely.

Unless the original design was converted from inches at some stage? Even then you migh find you can match up some common sizes. 1" = 25.4, 2 " = 50.8 etc.

Cheers

Fred W B

Why not use the Rubbing Method on Milimetric Paper (??)
A paper with mm markings on it. Then scanning, then the grid will give you an accurate placing of the hole center distance.
HTH.
AA

The distance between the edges of the holes will be the same as between the centres if the holes are of equal size.