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Chat Area => General Car Chat => Topic started by: aaronjb on 17 January 2019, 14:00:02

Title: One for the Engineers in the room - head skimming
Post by: aaronjb on 17 January 2019, 14:00:02
Random question of the day:

Dedicated machines for skimming heads exist - they look like big single-purpose milling machines, to me, with a giant fly-cutter head.

Is there any reason you couldn't strap a head down to a suitably large general-purpose vertical mill (like a Bridgeport) and skim the head with any fly cutter large enough to clear the complete head surface? I can't think of one, but maybe I'm missing some Machinist Devilry..

</random thought of the day>
Title: Re: One for the Engineers in the room - head skimming
Post by: Doctor Gollum on 17 January 2019, 14:19:34
Could the weight of the head pull the support plate of vertical far enough to cause a discrepancy one end to other :-\
Title: Re: One for the Engineers in the room - head skimming
Post by: aaronjb on 17 January 2019, 14:46:58
It's possible that a Bridgeport wouldn't be rigid enough - heads are sizeable castings and I don't know (since I don't have one, sad times) what kind of parallelism and accuracy you could get out of a well maintained Bridgeport (knackered old examples excluded, obviously, which is probably most of them at this point!) vs a head-skimming machine..
Title: Re: One for the Engineers in the room - head skimming
Post by: Nick W on 17 January 2019, 17:24:39
If the mill is properly trammed, and has enough table travel there's no reason why you can't skim a head with one.
Just like you can bore a motor cycle cylinder in a lathe.


The specialist equipment for this sort of work is to save time, and make a better job easier.
Title: Re: One for the Engineers in the room - head skimming
Post by: aaronjb on 17 January 2019, 19:28:52
If the mill is properly trammed, and has enough table travel there's no reason why you can't skim a head with one.
Just like you can bore a motor cycle cylinder in a lathe.


The specialist equipment for this sort of work is to save time, and make a better job easier.

Thought that would probably be the case ..  :y Not that I'd fit anything but a tiny bike pot on my little Myford ;D and I farmed my engine work out to someone who knows what they're doing.. but I was curious :)
Title: Re: One for the Engineers in the room - head skimming
Post by: Nick W on 17 January 2019, 22:33:31
If the mill is properly trammed, and has enough table travel there's no reason why you can't skim a head with one.
Just like you can bore a motor cycle cylinder in a lathe.


The specialist equipment for this sort of work is to save time, and make a better job easier.

Thought that would probably be the case ..  :y Not that I'd fit anything but a tiny bike pot on my little Myford ;D and I farmed my engine work out to someone who knows what they're doing.. but I was curious :)


A car cylinder head is going to really stretch a Bridgeport size mill, as you need a cutter large enough to cover the width in one pass and enough table travel to clear both ends. Fixturing could be tricky too.
Title: Re: One for the Engineers in the room - head skimming
Post by: Marks DTM Calib on 18 January 2019, 07:33:29
Of course you can, the guy I used to get heads skimmed by had a big Bridgport and used nothing else (and he skimmed stacks of heads), when measured after they were spot on.
Title: Re: One for the Engineers in the room - head skimming
Post by: aaronjb on 18 January 2019, 09:08:13
*pines quietly for a Bridgeport, knackered or otherwise* ;D
Title: Re: One for the Engineers in the room - head skimming
Post by: Nick W on 18 January 2019, 16:35:56
*pines quietly for a Bridgeport, knackered or otherwise* ;D


It's not the mill, but having space for one. I bought the biggest lathe I had room for, and it's still a benchtop job; I don't really have room for the mini-mill, but it's necessary. I'd like a bandsaw too, and a permanent spot for the benchgrinder that isn't a shelf over the cellar door....