View Full Version : Why are most cutters so crap?

16-10-2015, 03:40 PM
I need to route 9mm birch plywood. I didn't have a straight flute 6mm cutter so to get on with the job I went to B&Q and got one of their 'JCB' bits. I was only cutting 4.5mm per pass and it broke off like those cheapo bits from ToolStation etc.. that are 1 each. This was 8! I took it back and got another. Worked for about 1 hour and broke in the same way.

I took it back for a refund and get a 'Trade Range' Trend cutter from Screwfix which happens to have opened near me recently. Looks good, nice short 16mm cut length. It cut for less than 20mins and part of the TCT insert has come out.

Seriously, can't they make good quality anymore? I used to think Trend was good. Looks like only solid carbide for me now!

Is 6,000 mm/min at 4.5mm doc too much to ask for a 6mm cutter? It's only birch plywood! G-Wizard says it should be okay for a 'HP HSS End Mill'.

16-10-2015, 06:04 PM
what rpm ?

16-10-2015, 06:41 PM
I was using 16K rpm.

Christian Knuell
16-10-2015, 06:54 PM

have you checked spindle runout or are there strong vibrations? Excessive runout and vibrations kills even the best bits in little time.


16-10-2015, 07:27 PM
I don't believe it's a problem with the machine, I have done nothing that should knacker the spindle that was working fine with my other cutters, even 3mm dia. ones.

That said I've asked Trend what feeds and speeds they recommend and they said 4.5mm DOC, 4,500mm/min and 18-24K rpm. Im my mind that is a very small chip-load that I'd expect to cause re-cutting of chips and excessive heat build up.

Anyway I've got these on order, so it's a temporary problem. http://www.ebay.co.uk/itm/231688045601?_trksid=p2057872.m2749.l2649&var=530910370329&ssPageName=STRK%3AMEBIDX%3AIT

17-10-2015, 01:51 PM
I find with cutters you really do get what you pay for and the higher quality Carbide are worth every penny. Trend I don't exactly class high quality.

There's also much more to cutter than just HSS or Carbide. Flute type, angle etc play massive part to how the cut on CNC machine and with different grades of material. The grade and quality of Board for instance can make big difference, high glue content or low grade cores etc can kill cutter quick.
Cutters designed with CNC in mind and aimed at specific materials have flute profiles and angles etc that deal with the extra forces imposed much better.

Then you also have spindle to throw in the Mix.? . . . . You say 16000rpm but are you actually maintaining 16000rpm in the cut.? Has the spindle got enough guts so it's not bogging down when the going gets tuff.?

All these things make up the Big picture and it's easy to blame the cutter when it's actually some other reason.!!