mech engineers/cnc machinists - straight edge

resto_d1 · Apr 1, 2020

Hi gents

After a bit of advice. I am refreshing a 300tdi head. The initial thought was to get it in the machine shop and checked for flatness. However, it looks like its been refaced in past and engine ran ok prior to taking head off. I took off due to the cooling system being a bit nasty and to decoke.

Anyways, The mech assemble is something I really enjoy and I need some accurate tools. I will buy these in stages -internal mics, dti etc.

This months purchase will be a straight edge to assess flatness. Does DIN 874/2 cover my requirements for a straight edge? I've studied mech in brief as a kid but out of touch. I don't want to buy something not good enough for my needs but also don't want to break the bank. I am assuming it does as the particular one I'm looking at gets down to +/-10.5 microns.

Any advice, especially from the old school dying breed appreciated!

Thank you and stay safe

Kev12 · Apr 1, 2020

I'd say thats plenty good enough, your technique to measure will have a higher tolerance than that

potus · Apr 1, 2020

To be honest, if its just warped cylinder heads you want to check for flatness, a lenght of ground flat stock will probably suffice but this may not be that cheap anyway, otherwise just go for a basic engineers 'straght edge' seem to be around £40 for a metre long.

resto_d1 · Apr 1, 2020

thank you both. It is checking the cylinder head, yes, and also checking piston protrusion, however, will no doubt come in handy for welding projects and the odd woodwork job should I learn the patience if working with wood!

RangeRoller dt · Apr 2, 2020

You can get a little seat to sit a dti gauge on too. Can see the different values as you move it along the head

raywin · Apr 2, 2020

Should be more than adequate, if you are going to lay it on the surface and test by trying feeler gauges under it,.
Dont get one that's too light it makes checking more difficult.

resto_d1 · Apr 2, 2020

raywin said:
Should be more than adequate, if you are going to lay it on the surface and test by trying feeler gauges under it,.
Dont get one that's too light it makes checking more difficult.

I was actually going to ask you as been following your thread and noticed you had some nice tools! Especially your mic! Is the motor all running nicely?

raywin · Apr 2, 2020

resto_d1 said:
I was actually going to ask you as been following your thread and noticed you had some nice tools! Especially your mic! Is the motor all running nicely?

Yes thanks, it seems to be settled down nicely and running better than ever about 1500 miles now but I dont use it every day.
Were you having problems with your engine? Just wonder what made you decide to do the work, or is it just an isolation project.
Most of my tools are left over from my work, but you can pick up stuff on ebay these days quite cheap, but look for good makes like M&W they stay accurate long after cheap stuff fails, inaccurate readings can be pretty costly.

resto_d1 · Apr 2, 2020

The coolant system was in a nasty state and didn’t know the history of the car. Engine is on 160 odd so wanted to see where it was at and yes it was a spur isolation project

raywin · Apr 2, 2020

resto_d1 said:
The coolant system was in a nasty state and didn’t know the history of the car. Engine is on 160 odd so wanted to see where it was at and yes it was a spur isolation project

Mine had a damaged cam lobe when I bought it and at 120k miles I expected to find wear in other places, it was quite a surprise when I measured the crank, and bores.
Good luck with your rebuild hope it goes well.

resto_d1 · Apr 2, 2020

Yeah it’s an impressive thread mate and proves that the td5 isNt the devil!!

rob1miles · Apr 8, 2020

It won't be that easy to check the head with a straight edge, it will pick up curves ok but high and low spots or a twist will be harder. If you use a wide type (ie camel back) they are costly. Ideally you want to put it on a surface table and run a dial gauge over it. I would look at the old gasket, it will tell you a lot, if that is ok, even thickness and no burning then the head should be ok, if its not ok there's no point measuring it as it has to be skimmed and the machine shop will do that. You can use the block to check as well, that what it has to fit. Can you do the piston protrusion with a Vernier caliper? I wouldn't use the same straight edge for welding and for checking.

resto_d1 · Apr 8, 2020

Thanks rob, gasket was good and engine wasn’t smoking or anything. It didn’t know it’s history and when stripping coolant system was manky so thought I’d whip head off and freshen up. I got a laser straight edge in end that goes down to 0.03 tolerance and couldn’t fit a 0.05 anywhere on it. Yes, agreed, camelback would’ve been nice but couldn’t warrant it as not used enough.

mech engineers/cnc machinists - straight edge

resto_d1

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Kev12

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potus

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resto_d1

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RangeRoller dt

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raywin

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resto_d1

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raywin

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resto_d1

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raywin

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resto_d1

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rob1miles

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resto_d1

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