Extreem Pocketing and profiling

[rhfurniture]

Hi,

I am trying to cut pockets and profiles about 140mm (5.5") deep in solid African Bubinga, using a 3Kw spindle So far the best results we have had have been done using 170mm 16mm up-spirals eased in very gently with very light cuts, however through vibration, the main problem is the router bit pulling itself out of the Collet. I have tried straight deep pocket cutters with the same result
I am thinking of having a 16mm dedicated collet that I "glue" onto the cutter using some form of locktite. Has anyone tried this approach - any suggestions or experience most welcome.
PS please don't tell me it cannot be done......

Ralph

[jerry_stanek]

It sounds like your collet is worn out or the wrong size. If you are using metric bits you will need Metric collets and not the multi size ones. get a good quality collet and see how that works. It may even give you a smoother cut with less run out.

[kubotaman]

Although 5.5 is quite deep it may be nothing more than vibration which would tend to make it quite hard for the collar to hold on. You may try using Her-Saf cutters. I have used them quite a bit They will make you an extra long spindle at a really fair price. I have had them make me one 5 inches long without any problem. Give them a call.

[Bob Eustace]

Like Jerry I have found a new top quality collet solves walking cutter problems. I also adhere to Bradys advice - buying cheap collets is the formula for continued grief etc. Another thing worth trying is putting conduit extensions on the spanners - works well if you have arthritic hands.

[rhfurniture]

Hi,
We are by default using UP (5 micron) collets that cost £32 (at least $50) here in UK. What I have relaxed a bit on is throwing away both bit and collet following a slippage (a very expensive practice) so we are starting again Monday with a whole new set. I assume that slipping causes damage - what does everyone do?
The collets I have used are 16mm for 16mm shank and 13mm for 12.7 (which also slip). My suppliers just say that I will not solve it without a heavier spindle & collet build, ie ER32. They may be right, but I would like to explore other options first.
I have also seen reference to torque wrenches on the forums. What torque do people use? (I assume it varies by collet size). Also, does anyone have a good source of the wrenches? - I assume I am looking for the socket in the end type rather than square drive.
I am also looking for an insert tip 170-180mm (7 inch +) total length bit with a shank diameter less than cut, so I can sink it right up to the collet.

Any help most welcome, Thanks, Ralph

[sailfl]

What depth are cutting on each pass? What Feed Rate and spindle speed are you using?

[rhfurniture]

Hi,
Current most workable is 13mm depth, 2mm x/y cut from an open side (the pockets are dovetail sockets and pins), about 4200mm/min (this machine uses mach3), about 14krpm with 2 flute. Anything more and the cutter pulls. Never goes more than about 1 amp over idle.

Ralph.

[harold_weber]

Hi Ralph,

Techniksusa dot com sells ER torque wrench adapters. I have no experience with the adapters, but I do buy their collets for my Perske spindles.

Harold Weber

[rhfurniture]

I realized that the torque wrench doesn't have to be anything special as the torque stresses are equal and opposite however far the nut is away from the measuring point (I had thought that the geometry was crucial) so I cut a square hole in the handle of my ER nut wrench and am using my regular square drive torque wrench. IF ANYONE KNOWS DIFFERENT please say.
The result is that I found I had only ever tightened my collet to 20 ft lb max - its a miracle I ever kept a cutter in that thing. I thought that the ER wrenches were short for a reason!
Now we are up to 80 ft lb (as in the top page of http://www.rego-fix.com/er-system/pdf/collet-torque-chart.pdf) and all seems much much better.
Thanks, R