Balancing Drill-Holes on Tooling
Cutterheads may be balanced at the factory by drilling small holes to remove weight. But that won't salvage a poor-quality cutter. September 10, 2007
Question
I recently purchased a raised panel cutter from a woodworkers supply house. When I got it I was very surprised to find that it was riddled with small drill holes in the sides of the body. One of my friends assured me this was normal and was done to balance the tool. So the next day I put the tool on my shaper and started it up. My shaper shook so badly that it darn near vibrated my teeth. Has anyone else ever had a cutter like this?
Forum Responses
(Solid Wood Machining Forum)
From contributor D:
I have seen tools like that in the past and they were some Chinese made junk I bought from a supply house. I sent mine to a cutter manufacturer and they told me that the body was poorly milled. The original manufacturer had tried to drill holes all over the thing to balance it. Mine vibrated badly in spite of their efforts, so I sent it back to the supply house for a return. It doesn't pay to buy cutting tools on the cheap. As you may have heard, "You get what you pay for."
From contributor J:
I agree. I had a customer bring in his own 1/4" knife stock he wanted his profile ground on. They were from a cheap woodworkers supply place. I couldn't even rub the two corrugated faces together. Unusable. It pays to pay more for tooling. Or at least stay away from the cheap stuff because it is just that.
From contributor A:
It is common practice to drill one hole when balancing a cast cutterhead. The key word here is one. The depth of the hole determines the balance. More than one hole, then it is junk.
From contributor R:
I would like to respectfully disagree with contributor A. When cutter heads are balanced, the steel is taken from where the steel density is too heavy. I have seen cutterheads with many holes drilled in many different areas and they run very smooth. May I also add that the gibs, gib screws must also be balanced.
It is on the same theory as balancing a car tire. You can't put the weight where you want to. You must put it where it needs it, and sometimes there are two or more weights on the tire.
May I also state there are good cutterheads from all over the world as well as inferior ones. In general you get what you pay for. Buy from someone you trust and who has a good reputation and they will take care of you even when things get like this. Even the best manufacturers have had some lemons in their inventory from time to time.
From Dave Rankin, forum technical advisor:
Contributor R is correct. When balancing heads it is common to see several balance holes. The larger the head, the more common it is. This is necessary when dealing with a 2 plane balance issue. For example, on a 6" long cutter, the right side may need balanced at knife pocket one while the left side of the head body may need a balanced at knife pocket 3.
If not balanced correctly, the head will try to run in an egg shape. The high point of the right side will be on top while the high point on the left side will be on the bottom. In tooling, you generally get what you pay for.
From contributor A:
I should have been more specific. I was referring to holes in a small cast cutter like the mentioned raised panel cutter. I'm aware that on much larger, very accurately made planer heads like you mentioned, it is common practice to drill several holes. Because it would be impossible to drill one hole deep enough to balance the head.
