Question
I run moulding in a small shop. I am currently running a Profimat 22n 4 spindle machine. My problem is an inferior finish on the top and bottom spindles. The top seems to be the worst. I have done everything I know to do: level machine, align fences and infeed table, new air cylinders, new cutterheads, both spindles are within 2 microns runout, tightened and reset dovetails, new belts, retentioned belts, set all drive wheels to same height (according to scale), checked balance of gibs and knives, made sure tooling is all sharp.
Still, I get chatter on any flat surface (s4s, t&g, base, etc.). My profiles seem to do better since I use formed pressure shoes I pour myself. The machine is set up very similar to the new Profimat 23e, except for the pressure shoe being 1.5" wide and mounted onto a piece of spring steel (unlike the large steel one used on the 5 spindle machine). The biggest disadvantage is the chain drive system (even though it is a 1986 model?). The feed seems to run smooth without any jerky movements. The one thing I have found is some slight wear in the bedplates. They are flat across (no dips), but are about .002 difference from side to side. Is this enough to cause my problem?
Forum Responses
From contributor M:
You have not mentioned one of the more important adjustments. Is your pressure plate parallel to the bed from front to back? Even though you have custom fit to profile, which would be a definite advantage if your plate is not parallel, it really won't help a whole lot.
Inconsistency in knife marks is a sign of vibration. Are you getting this, or is there some sort of consistent pattern to your problem?
Another problem I have experienced on our Profimat is that the operators fail to tighten the spindle after making an axial adjustment.
You could also look into the spring assembly attached to the pressure plate. Is this working properly and free of obstruction?
Only .002 difference from side to side should not cause a significant problem. I have seen them as much as .020 and still running.
The pressure plate is Mickey Mouse. It is not on a dovetailed way like you're used to. The main bracket that adjusts the height bolts to the hood. Once your height is set, you lock it down. The spring action is provided by a piece of spring steel mounted to the main bracket, cantilevered out 3-4" under hood to meet top head, with small 1.5" x 7" pressure plate bolted to it. The spring action does not move perpendicular to the bed. It moves up at an angle (bends back), therefore the pressure plate is milled at an angle to compensate for this. The nose of the plate is lower than the rear when it touches the board (nose touches first), and as you keep on putting more pressure, it flattens out. If a board passes through not back to back, the pressure element nosedives, and the second board can sometimes jam. To eliminate this problem you must raise the pressure bracket. When you do this, the rear of the shoe is off the work piece. You cannot get equal pressure on the front and back of the 1.5" wide pressure rail.
Have you encountered anything like this?
In most cases, the problem can be repaired with a simple machine tear-down and clean-up.
Dave Rankin, forum technical advisor
Are you talking about the self-locking nut that threads into the spindle barrel and has the shoulder for the cutterhead? If so, these have been set to reduce the spindle runout to near zero. Would this put them square?
Even if I were to fix these problems, do you think a quality finish can be obtained?
If the machine is gone through and all the internal adjustments are cleaned, it should work fine.
Dave Rankin, forum technical advisor
The description you have given of the very slight chatter problem makes me think you have a spindle problem that the great Weinig did not catch. A lot of Weinig spindles that I have dealt with do not have tight enough tolerance on the spindle housing where the outer race of the bearing fits. This will cause the problem you have described, even if the setup is perfect.
I noticed you are using new heads. What brand of head and what style are you using? If you are using a straight bore head and the spacers have any dents or dings, this will allow a spindle to distort when you lock the head on the shaft. In testing, we have found that we could distort a 1-13/16 spindle as much as .024 runout with slightly dinged spacers. Install a five-inch wide straight knife head on the top and bottom spindle.
Use a good straight edge a half inch away from the inside fence and set the bottom head. Now come to the outside of the bottom head and check the setting. If these are not exactly the same, this will cause the problem you are having. Repeat the same procedure for the top head. The bed wear is to the point that if you have not compensated for it you can also have the chatter problem.
In the last place I was, we rebuilt five of these. The tables we had surfaced and a special coating installed on the bed plates. The coating outlasts chrome by four times, and had half the coefficient of friction. This made the machine feed easy and eliminated chatter.
Comment from contributor A:
Check your sprockets teeth and chains. If your sprockets are worn, the chains will ratchet as the links go over and hook in the links, causing a jerking motion in your feeding of wood into the machine.
We were all staring at this moulder one day and thought maybe how it was sitting on the floor was causing the chatter. It had the original pads it sat on, which are pretty small, so we thought we would try some nice new rubber pads like we use on all our Diels. It was 100 times worse!
So we took those off and cut some nice thick steel pads and it was 110 times better. So we were on to something. 4 months ago we poured a new concrete pad for the moulder. 14 inches thick and 2 feet wider and longer than the moulder on both sides. Wow, what a difference. The little bit of chatter we had before was now gone. Now we get a glass-like finish on all the parts we run.
