Machine shop deburring
 

Hello All,

I just took a good look at my 2.2L case which came back from the machine shop last week. After spending almost $2K on machining at a reputable Porsche-only shop, I was a little surprised to find some nasty burrs on machined areas. I can't imagine assembling the engine without carefully deburring all ragged and sharp edges in the interior of the engine. Those little chips will wreak havoc if they're left to drift around inside. Is it typical for machine shops to leave that for the customer to do? I don't recall reading in the usual books or on this forum any description of having to spend a couple hours deburring after getting parts back from machining.

Here are examples:

The first main bearing saddle:

http://forums.pelicanparts.com/uploa...1337539188.jpg

Oil squirter:

http://forums.pelicanparts.com/uploa...1337539211.jpg

Relief for crank:

http://forums.pelicanparts.com/uploa...1337539246.jpg

Oil pump joint:


http://forums.pelicanparts.com/uploa...1337539292.jpg

Thanks for your input.

-Paul

Hi Paul,

Normally, its the engine builder's responsibility to do the cleanup and prep after machining operations as this critical detail should not be left to anyone else.

I'd love to know who did the work though, as I've seen much better.

I wonder if your case was mistakenly listed as completed..put in the wrong pile? I would like to know who did the work as well.

Not acceptable...

Sorry for your disappointment
 

Not pretty. I do my machining and cleanup, and so am not experienced in drawing a line between the 2 jobs. Last time I had a shop help, 42 years ago, with careful written instructions for cleaning up the head contact surfaces on a pair of 356B heads, with "bore until the surface is clean, then go the same depth on the other bore, and repeat on bore 1 until both are clean, with a limit on the depth of the whole job, and the clear instruction not to take off more than a light cleaning. The shop bored to the trash-limit, and ignored my typed and verbal instructions. At that point, I began to carry out all my own mill, lathe, press etc operations. I do trust others for crank grinding, and rod sizing where needed, but not much else.

Getting rid of burrs is important, but not so much as cleaning out all the oil passages etc. Drilling out and replacing all those alloy plugs, plus a good solvent rinse, and air/ water / air. I get carried away with this, but for good reason. It might be tempting to have a 'shop' clean up, but I do not trust anyone to be as picky as I am.

Thanks for all the comments. Time to have a word with the machine shop. I'll post back with their response.

Thanks again.

-Paul

Had a set of rods recently reconditioned and found similar. Nice machine work (everything checked out good with my check of their work) but upon disassembly in preparation for installation onto the crank, I found quite a bit of grinding residue in the thread areas of the rod big ends. I was burnishing the new rod bolts and felt one of them have some crud in the threads. So I cleaned them all up with carb cleaner and started fresh again.

Proof once again that you have to double check the work done for you and always always ALWAYS make sure things are very clean. You've got too much at risk to assume your parts are ready to install as soon as you take them out of the box.

Epilog
 

So... I spoke with the machinist today. Their view is that the engine mechanic is responsible for deburring, cleaning,inspection and any other final prep of the cases prior to assembly. I agreed with that except the part about deburring, which I think should be done after machining but before cleaning and closing up the oil passages.

He offered that they can do the deburring but it would have been an extra 2-4 hrs at $100/hr. added to the bill. I might have considered that if it had been proposed at the start of the job, but it wasn't discussed. I had them do everything they recommended so it's not like I was a skimping or alarmed about their prices. We agreed to disagree about whether or not removing ragged burrs should be part of the machining service.

Anyway, I'm over it. I'll take care of it and I don't want to mention names or provoke any further argument with the shop. Next time I'll know to be more explicit about what's going to be done.

Thanks to all who read the post and shared their comments.

-Paul

Paul, you are one cool customer. I would have been royally pissed. You're right, though, it's better to just go on.

I guess I could live with the task of deburring, but it doesn't look like their tools were very sharp...

Brrr !
 

It is near freezing this evening. ;-)

I agree that this seems like a lot of bur-bits per cm of cut. With a given degree of stock hardness, a dull tool and improper feed-rate will make more of this 'problem'. I believe that if the quote were to include getting rid of burrs, then there would also be an incentive to use techniques to minimize this. Running a lathe tool into the sharp corner of that bearing saddle takes only seconds and leaves a tiny chamfer. No hours of hand rework needed. I have a project involving welding 6061 T6 and machining it. I will be taking it back to T6 condition before I start milling and boring to size. I have never liked to do any machine work on freshly welded 6061. :(

I have had to pay more or get less with shops on occasion. It may make me less inclined to go back, or to be more careful. I see zero benefit to leaving a shop with sharp words, no matter how annoyed I may be at the time.

Hi KTL: As I reported in my red river sports car enthusiast newsletter, the last rod resizing I had done taught me that Verbus rod bolts can be installed backwards. Mr Google can find it for you on its FB page and free.yudu. The biggest local specialty shop here cleans and shrink wraps cranks and rods. :)

David

Wow, that oil squirter looks awful. I ran my own business in that field for 4 years, a small 15 employee subsupplier to the automation industry, and I would NEVER have left it like that. Deburring was ALWAYS included in the price I gave, unless the customer specifically told us not to deburr. Which never happned.

Seriously, that machine work (oil squirter in particular) seems to have been performed with dull tools or improper setup. Have you really sent the owner of the shop a pic of that oil squirter? And he still won't accept any responsibility? That is just very surprising.

Deburring is an art, made with very elaborate and fairly expensive tools. We used compressed air driven hand-held grinders. Another option would be to deburr in the mill, but that requires CNC machines. Then the deburring is done in seconds.

Much of the deburring needed according to the pics above is not for everyone to do.

You are right to move on, its just a days work for you, but you should consider disclosing the company to help the next fellow pelican.

I would welcome a comment from the company itself.


Regards,

Johan

I am calling BS on the machinist not being responsible for the deburr. I don't care if it is automotive or general machinist, the job is not complete until deburred and cleaned of chip debris. That is lazy and sloppy. You need a new machine shop IMHO.

Looks like a half-ass job. Another thing to consider.... If you do your own deburring, and something (bad) does happen, the shop will hold you responsible for doing your own work.