Climb Cutting on a Moulder
Molding manufacturers discuss the potentially dangerous but sometimes necessary practice of climb cutting. January 22, 2006
Question
I run a Weinig Unimat26 6-head molder. I have had some tear out issues on hickory flooring and have been unable to solve it completely. I have 2 bottom heads removing material from the face, the last taking around .020". Both heads are helical with carbide inserts. I would like to reverse the rotation of these heads and see if climb cutting on the face would help. I was going to start with the last bottom head, as it is removing the least material. The only problem I have heard of is dust collection not working properly. I would love to hear any experience with climb cutting with a molder.
Forum Responses
(Architectural Woodworking Forum)
From contributor R:
Do you value your life? Climb cutting is extremely dangerous and not recommended. Have you tried 12 degree hook angle heads? They should reduce the amount of tearout you're getting. But I can not stress enough: do not climb cut! That lumber will come flying out of your moulder at the speed of light.
From the original questioner:
I fully understand the dangers of climb cutting, but the position of the last feed roller and the last cutter make this viable. Weinig offer reverse rotation as an option. So I figure someone is doing it. Also, the last head removes a very small amount of material. I just wish the company I worked for would not sell pristine floors that require such drastic measures, but such is the industry.
From contributor R:
Do you have any anti-kickback devices on the machine? Do you realize the force that those rollers are going to receive? Please contact Weinig and ask them about what you want to do. I am sure you will be lead away from doing this. You will have to have many safety devices installed before you attempt this. Be prepared to pay a lot, as this type of operation is not common.
Please try 12 degree hook angle cutterhead with straight carbide tooling. I am sure you will see a difference in your finish on the chipout.
From the original questioner:
Which company offers a carbide insert straight 9" (planer) head with a 12 degree hook angle? I have tried the Weinig 4 knife insert heads with no luck and the helical carbide heads are what we are using now. I am sure they are over 12 degrees, but do not know and have not measured them. The helicals are better than the straight knives, though. They were recommended by Weinig. I am not locked into climb cutting, just looking for a solution.
From contributor S:
Some years ago, I had the opportunity to run a Weinig 22 that was factory equipped with reversible spindle rotation switches on five of the spindles. During the time I ran the machine, I felt compelled to use this feature exactly once, to solve an issue much the same as yours, tearout. While I can't remember what species of wood was involved, (might have been maple), this did do the trick at the time. The dust collection system on this machine was extremely good, so I had no issues in that area.
The safety concerns are warranted, although I think any of your flooring that accidentally exits the machine will do so at somewhat less than the speed of light. Take all precautions necessary for a safe operation.
From the original questioner:
From other threads I have seen, there seems to be an unjustified paranoia about climb cutting. I climb 99% of all of my shaper setups (nothing free hand, of course) and have done so for around 14 years. Never sent anything flying. I see more accidents on the table saw than anything. My main concern with climbing in the molder was dust collection, as this is what Weinig had mentioned. That was the main reason I wanted to start with the last head. This has to do with the angle the shroud is in relation to the direction the chips take. From all of my years, the most serious accidents have come from table saws and gang-rip, straight line saws.
From contributor R:
Look into just a straight knife inlay or double back carbide at 1 1/2" wide suitable for your needs. Sure, you will have to sharpen them, but I think it will be cheaper and safer than climb cutting in the long run. I'm glad I got my point across about how fast things can happen around machinery. I have shaken a lot of hands missing fingers in my days. I am proud of my safety record and would not recommend something to you if I would not feel comfortable doing it myself. Some people would be fine doing this, as stated. This is my opinion. Be safe and maybe somebody else knows where you can get a 12 deg hook spiral or helical.
From the original questioner:
Contributor R, you just reminded me that we ordered some backed carbide knives to fit in our moulder heads. These were 45 degrees to set up a miter fold jig in the molder! Very interesting. Anyway, getting straight knives would be no problem, and then I could use the 12 degree pocket heads we already have.
From the original questioner:
Did some climb cutting with the molder today! Worked perfectly. If I had done this months ago, it would have literally saved thousands of dollars. Not only did I lower the waste factor, I was also able to increase my feed rate. No dust collection problems and no impalement! Best of all, the owner was very pleased.
From contributor M:
I also don't recommend climb cutting. Having said this, I run a Weinig moulder (as well as a smaller single head Woodmaster) and I think that the problem with tearout is the helical head for your finish head. We only use our helical head on the first bottom and not on the second bottom. We were told long ago by our Weinig rep that the helical head just won't cut it as a finish head (so to speak!).
From the original questioner:
I have tried running just about every head configuration to solve this problem. I am running around 115,000 lf of 7" face hickory floor. This is running face down. The face has to have no tear out and be perfectly clear! The helical heads were recommended by the tooling department of Weinig, as they are less likely to tear out. They do give lines and other undesirable marks, but being that it is for a floor, we are timesaving and pre-finishing it anyway. Straight planer style heads were tearing badly. Then the helical did improve things a great deal, but had to stay sharp and be run slow. Now with the climb, it does not matter, as my feed rate is back up and the tear out is almost completely eliminated. It only exists around knots, which are getting defected out anyway.
From the original questioner:
I am having switches installed so that I can climb with both bottom heads. I usually remove about 2.5 mm off of my first bottom. At least at this area, the board will have to find its way all the way through the machine before coming out.
