Question
I have a question regarding effective life of straight bore cutter heads. We have some tooling that is still in use as of 20 years. I can't help but think I should be looking at replacing a few of these with new items. I am thinking about all the constant stresses involved. I know it can't hurt to change them I’m just interested to hear what you other guys do and if you have a max service life or when you do say enough is enough.
Forum Responses
(Solid Wood Machining Forum)
From contributor J:
I would replace any head that has been in an impact. This should be fairly easy to tell, damaged gibs, head body, or big dents are most common signs of damage due to impacts. Once damaged, who knows the extent of the damage, there could be hairline cracks which might not cause a problem for a long time, then boom! I would also replace heads that have oversized bores, if the bore gets to sloppy over time you could end up with one getting seized on the shaft. I have seen many people use cylinder hones to
clean up the bore of a head.
1. For heads with four or more pockets; have all of the pockets had knives or gibs in them at all times they were being used. If not, then you could have some potential damage of the body.
2. Size of the head. Most profiles use 4" heads and under, so these are the heads that should be looked at first (unless you have damaged heads).
3. Manufacturer of the body. There are many brands of head bodies that have to be considered. I think Mike, that most of your heads are Weinig. If so, this is one of the top brands. They use top quality metals and hardware. Some of the other brands including some imports and domestic use top quality materials while others do not.
4. Screws. If you have used a process where the gib screws were tensioned properly (correct torque and wrench size, etc.) then you most likely have not damaged the threads.
5. Bore of the tool. As already stated, the bore is critical. I use a bore test gauge to assure that the bore is correct.
6. On corrugated heads check the condition of the corrugations.
I measure the spindle with a micrometer and the spindle with an inside caliper or gauge block set. The set includes as exact size, and 1 each of .001" over and under. Tolerances vary between machine brands and cutterhead brands. If you stay within the tolerances above on new tools you should be good to go. I have had 1 manufacturer that made the cutter head bore so tight that the tool had to be returned to be opened up a little.
In general, the spindle is to be the exact size and the cutter head slightly under. If you use a good manufacturer of heads you should be fine to run from the box, I do check the gibs for balance. I check my tools for wear when I change the tools and do a complete examine including bead blasting about one per year.
