What do these things do?

[Rik ShawParticipant @rikshaw]

Having been out of touch with modern engineering techniques and tooling for a good number of years now I am frequently coming up against stuff I have no knowledge of.

A good example is shown in the pics. I bought nine of these solid carbide drill/reamers of various sizes from the car boot for a few quid. All are brand new and the one shown is the largest at 8mm diameter. I have never seen anything like these cutters so I seek enlightenment.
They are made by UK company Lomas and as far as I can make out are for use on exotic abrasive aircraft plastics – am I right? If they are unable to machine steel or brass they will not be a lot of use to me and may as well be moved on.

Is there a particular reason why the shanks are so long? The one pictured is 150mm long and its part no. is ST1257B-3125-60-1. It is described as ""VHM drill reamer". What is VHM?
Rik

[Rik ShawParticipant @rikshaw]

Stuff thats to clever for me!

[Michael GilliganParticipant @michaelgilligan61133]

Rik,

I would guess that VHM = Very Hard Metal

Whatever … that's a lot of useful-looking Carbide !!

MichaelG.

[Sub MandrelParticipant @submandrel]

GIYF

That number brings up a few results, including this page. One is for a different tool tech reamer which re-googled brings up an ebay seller who doesn't know what these are and a few links that suggest they are 'drill reamers'. I suggest spinning one up and pushing it into a small pilot hole and seeing what happens!

Assuming you survive the experiment, please report back to us!

Neil

[JasonBModerator @jasonb]

Looks like they are the one shot drill/reamers designed for composites like glass & carbon reinforced plastics. The tapered drill end is probably less likely to snatch and lift the layers of reinforcement.

**LINK**

[Rik ShawParticipant @rikshaw]

Update to original post.

Neil, at risk to life and limb I pushed one of these through a piece of 1/4" steel plate (no pilot hole) and it was like cutting butter. Following this barbaric treatment I had a quick peak at the cutting edges under the microscope. There was no sign of any damage.

By the way, I know the pics show that the tools have a gold coating — it's my light bulb that does that, they are the usual dark grey of carbide.

I have twigged that the "3125" bit of the part number is the diameter in 'thou's of the reamer ie .3125" . The others are .166" and .201" all seemingly non standard but maybe not so in the aircraft industry.

BAE might not buy their tooling on eb*y but if they do……………

Rik

[Cyril BonnettParticipant @cyrilbonnett24790]

**LINK**

This link might give you some ideas

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