insert spec RCMG60400F

[BWParticipant @bw]

Hello,

I want to investigate a round insert for a copying jig for a small South Bend clone lathe, 9" swing, max speed 720rpm. A round cutter might be helpful for some curves that I want to try and copy whereas a straight bit can be a bit awkward.

I dont have the skills to grind an appropriate tool from HSS, unless someone maybe has some tips ?

However I was wondering about making one from silver steel.

Tried to work out an insert spec and came up with RCMG60400F (left N off the end as its not normally used)

Tried searching on this but doesnt yield any inserts.

Searching on just RCMG however does yield results.

When specifying inserts is it customary to use just the first 4 letters and not worry about the rest ?

If I managed to make something from silver steel would it go blunt far more quickly than HSS ?

Bill

[BWParticipant @bw]

insert spec

[pgk pgkParticipant @pgkpgk17461]

The numbers at the end refer to the inscribed circle size of the insert.. in the case of a round one it's easy to appreciate. Then figures for thickness (I think), last figures for nose radius which here is obviously 00 and then a letter for the manufacturers code for their chipbreaker type.

Silver steel doesn't have the hot hardness of HSS so is more prone to suffering. Of course as a round insert you have lots of 'tip' to switch to. I made a simple flycutter from a round insert recently for the simple reason that I can run the mill way faster and hand turning the x axis becomes less of a chore but I doubt the finish is any better than i managed with HSS. In that case the insert was 10mm diameter coning down it's thickness to 9mm so was set into my DIY tool holder 4.5mm off the edge into a 10mm hole and held by it's required Torx screw

[JasonBModerator @jasonb]

You should be able to find RCMT easy enough or if cutting ali then RCGT, if you want to work into a tighter radius then the MGEH holders that ARC do can also be used to hold the MRMN inserts which have a 1mm radius to teh 2mm wide blade

[EmgeeParticipant @emgee]

Hi Bill, you could use round small diameter toolsteel in a purpose made holder similar to the Diamond tool holder from Eccentric Engineering who advertise in the RH column of this page.

Emgee

[John ReeseParticipant @johnreese12848]

I have seen posts of a tangential style toolholder using round tool bits. The bit was set at 12 deg. side angle and back angle. Unfortunately, I can not remember where I saw the post. Broken center drills or end mills are a ready source of tool steel for bits. The shape of cut produces by this tool will be elliptical rather than a perfect circle. Making a tangential cutter will allow use of narrower tool bits reducing the chance of chatter. Hope this helps.

[BWParticipant @bw]

Thanks for the advice. Will learn more about inserts. Was amazed at those tiny little ones referred to above.

Bill

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