Cutter Choices

Carbide cutters, insert knives, or high speed steel? Pros weigh in on the options. August 31, 2005

Question
It's time for us to replace our entrance door cutters (stile and rail). Our choices seem to be:
1. Renew our 3 wing carbide cutters.
2. Switch to inserted knife tooling.
3. Utilize our profile grinder using high speed steel.
Which way should we go?

Forum Responses
(Solid Wood Machining Forum)
If you do anything resembling a production run of these, the insert tooling is hands down the most cost-effective solution.

The difficulty with profile grinding is maintaining the fit over regrinds. Tipped tooling lasts longer between regrinds; however, having to send the sets out and regrind as a matched set takes time and a competent grinding facility.

The insert tool allows you to change knives in house and reduce down time. Patterns are repeatable from run to run. A flexible design allows you to use some different pattern knives in the same common head body. A higher grade of carbide knife ends up in better finish as compared to tipped tools.

Stark out of Italy stocks sets for shapers, moulders, and tenoners. Entrance door patterns can also be made to your pattern.


I grind my high speed steel by hand, so for me, cutting end grain with the cope setup would dull much faster in HSS than carbide. Since you have an automatic grinder, it might not be a big deal to resharpen more often. I am pretty sure, however, that grinding a well-fitting cope and pattern takes more skill than just grinding a profile. I haven't used insert tooling yet, so I can't help you there. High speed steel cuts wood more cleanly than carbide, but carbide stays sharp ten times longer.

Switch to insert tooling, especially for stiles and rails!

From Dave Rankin, forum technical advisor:
If your production requirements justify inserts, I agree with the others that insert tooling is the best way to go. There are many good manufacturers of insert tooling, so look around.

If you have medium production requirements, you may consider DGK ground to pattern knives. We are seeing normal run life of 30,000 lineal feet in hard maple with the DGK knives compared to under 3,000 with HSS. Carbide life will normally exceed DGK, but the cost is significantly different.

HSS $4-6 per inch plus $22 per inch or so to grind
DGK $6-7 per inch plus $22 per inch to grind
Carbide inserts $25-55 each plus the head body. Depending on the profile, you may use either a dedicated head or a universal profile head. $250-450 each, roughly.


What do the letters "DGK" stand for?

From Dave Rankin, forum technical advisor:
DGK is a patented heat reflective coating that is harder than carbide. The coating is only 7 microns thick and therefore it does not affect the sharpness of the cutting edge. DGK was first developed in 2000 and has been improved with the new 2004 version.

When put on HSS, the final tool can be ground with normal grinding wheels and when run in high speed applications is jointed using normal HSS jointing stones. The only concern is that you cannot hone the face of the tool, as this will damage the coating.
DGK is a product developed by the technicians at Moulder Services. It was first developed for hard maple but it was found that DGK runs MDF runs up to 6,000 lineal feet.