Na Píobairí Uilleann

[NeilO]

Greetings,

I had a tapered D-bit reamer made by a machine shop, the quality is second to none. One problem, it does not cut ! It has a 'cutting edge', meaning a relief cut off of the lead edge to improve cutting. It seams to cut better in the other direction, with the cutting edge on the lag side.
Also, does the size of the "V" cut out of the reamer make a difference in how it cuts. Please advise me of any answers. I'm at wits end with both why it does not cut and the small fortune I paid for it.
Neil
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[DLim]

Hi Neil,

Here's a possibility.

The milling process, by which the "V" was cut, may have left a burr along the leading edge. This could make the reamer more efficient when used in reverse.

If there is a burr you should feel it if you run a fingernail around the outside of the reamer and onto the leading edge. If there, it must only be removed by working on the "V" surface, not the outside of the reamer.

David
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[John Mulhern]

Hi Neill. Davids advice about checking for burrs is a good one. If it's still causing problems, could you possibly post a digital pic, or two, of the cutting edge...showing the relieved area? Also, if you could access a micrometer or dial calipers, could you please make two measurements at multiple points along the reamer...1) diameter across the cutting edges & 2) corresponding distance from the flat to the other side. (to see where centerline is) One way of verifying if an edge is actually cutting is to coat the reamer with some Dykem blue.(available at machine shop supply places...generically called layout blue) If, after attempting to cut a bore, the body of the reamer is shiny & the edge retained the blue...you gotta problem.
I think returning it to the shop, along with a pre-step drilled piece of wood, and letting them check it out, might be a good idea.