Spotfacing Tools

[Brian ThorbyParticipant @brianthorby32578]

I require a series of spotfacing cutters to suit hexagon nuts/washers on M6/M8/M10 sizes. I have searched online and the regular tooling retailers and all I get is the Counterboring Tools for Socket-Head Cap Screws i.e too small counterbore in relation to washer seating size of a regular bolt or nut.Can anyone suggest who sells such mundane tools, before I have to make a set ?

I am machining aluminium castings.

Thank you

[Brian ThorbyParticipant @brianthorby32578]

Where can I buy a range of spotfacing cutters as opposed to “Counterbores”

[JasonBModerator @jasonb]

You can get spot facers that take a range of interchangable pilots so you can adjust the size depending on the head/washer you are using, I know MSC do them but you should be able to find them elsewhere if you search for "Aircraft Spot Facers"

[JohnFParticipant @johnf59703]

Brian, why not make your own as and when you need them, just use a piece of silver steel the size of the drilled hole then make a 4 flute cutter to lock onto it with a grub screw. Made lots of these inthe past, you can also make countersinks and reverse spotface cutters, cutters can be sharp cornered or as is usual in the aircraft industry with a corner radius.

Doesn't have to be SS for the pilot you an use BMS or whatever, we used SS as a convenience.

Regards John

[John Stevenson 1Participant @johnstevenson1]

Arc does a set of the aircraft spot facers with interchangeable pilots so you can play mix and match.

[Anonymous]

Posted by John Stevenson on 12/02/2015 10:40:50:

……… with interchangeable pilots

Just don't let the co-pilot loose without supervision.

Andrew

[Brian ThorbyParticipant @brianthorby32578]

Thank you gentlemen for your so prompt suggestions.Arc's set doesn't go to 20mm cutter with a 10/10.5 dia pilot which is my first size objective.It looks as if I will have to make some,but will try MSC .Thanks again.

[VicParticipant @vic]

You need one of these. I bought this one at one of the shows.

[Anonymous]

Like this, spotfacing done with a 3/4" slot drill:

I've got one of them thar universal boring heads, on an INT40 taper. Mine's by Wohlhaupter, nice bit of German engineering and works a treat.

Andrew

[JasonBModerator @jasonb]

I suppose the one advantage of the proper item is that if you are using a drill press then the pilot will make it easy to line things up when you go back round after the holes to do the spotfacing, with a milling cutter you would have to set each hole under the spindle, clamp the work and then spotface which is not such a problem if you drill on the mill using a DRO.

I mostly just use a milling cutter and homemade ones for backfacing but I suppose if you had a lot to do then it would be worth investing in a proper jobbie.

J

[Neil WyattModerator @neilwyatt]

I have a half completed beam engine entablature where I milled off the baldly placed and formed bosses and epoxied washers on to replace them. is that cheating if I made the washers?

Neil

[JasonBModerator @jasonb]

Yes, you should have made a new pattern and got a new one cast

I've done that several times where a boss is cast a bit off or when I'm fabricating an engine, usually counterbore and turn up a new boss then use epoxy to get a nice fillet around it.

[Anonymous]

Posted by Neil Wyatt on 12/02/2015 19:49:01:

I have a half completed beam engine entablature where I milled off the baldly placed and formed bosses and epoxied washers on to replace them. is that cheating if I made the washers?

Neil

Not only that it'd lose you points at MEX for not being prototypical. Fullsize I expect they'd have just whacked off the lumps with a hammer and cold chisel and then tightened the nuts down – no faffing about with washers.

Andrew

[Ian S CParticipant @iansc]

On a full size agricultural machine that I build there are steps made from aluminium tread plate, and more often than not the bumps are right where the pop rivets should be, so I modified a flat wood working drill bit by rounding the centre spike to fit the hole, usually spot face in the drill press, but some times just use a portable hand drill. This works well with no chatter.

Ian S C

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