Shaper Chatter Marks

A shop owner tries all the usual troubleshooting tactics but it takes a brand new machine to solve the problem this time. December 14, 2009

A continuing problem. I have a 3 horse Delta 3/4" shaper. I've had what I consider bad chatter marks with all the cutters I use, all Freeborn. I thought it might be because it's only 3/4 until I'd seen some other Delta 3/4 shapers turn out very smooth rails, stiles and panels.

Put a new spindle cartridge in thinking it was the bearings. Nope, still just as bad. The runout of the new cartridge at the base of it is .001, which seems okay. Talking to Delta tech help, tried new belt, pulley, and finally I put a brand new Delta motor I've had for years in.

Still leaves chatter marks. I've lined up the spindle to the table. I can't think of anything else. Maybe the spindle itself, but there is not much runout with it. Does anyone have any suggestions to keep me from pulling out the rest of my hair?

Forum Responses
(Cabinetmaking Forum)
From contributor P:
Check your belts, pulleys and motor mounts again. .001 runout is well within reason. Be sure you do not have any axial play either. Next, how snug is the slip fit of the cutters onto the spindle? Should slip on snug without any shake. Shapers are simple machines. As long as the spindle runs true and the cutters are in balance, you should not have any problems. Do you power or hand feed?

From contributor C:
Chatter marks in general can be caused by the following:
Bad bearings
Belt tensions improper (normally too tight) - Are there any obvious seams in the belt? I've seen this be an issue as the seam travels across the pulley, resulting in chatter marks.

Tooling out of balance

I have had very good results in the past with Freeborn cutters. They are of a high quality. I would look at something related to the shaper itself, rather than the tooling. What species of wood and what is your moisture content? Contributor P brings up a good point on how you're feeding the material.

From contributor R:
I believe it's all in your feed method. Are you trying to hold the material tight to the cutter and fences? Or are you running a feather board or back side fence, which lets the cutter through it outwards away from the cutter and fence? Swap your method and change the RPM and you will be cooking with gas.

From the original questioner:
Appreciate the thoughts. I've always used a power feeder to feed the wood. As far as species, tried it with oak, soft maple, hard maple, birch and hickory. All the same results. Wood all 6-8%.

I wondered about the belt tension, so I tried to loosening at different tensions with no difference.

I agree with contributor C about the tooling. I talked to Freeborn about this problem I'm having and they were more than willing to check all the cutters to see if they have a problem there, but I doubt it as all my cutters do the same thing. I also tried the slower speed to see if it would make a difference. Nope.

As far as the feed method, I use the power feeder angled against the fence taking off 1/32" of wood for door parts. Is this what you meant, contributor R?

My Delta dealer is shipping me a new spindle to try to see if this is the issue.

From contributor L:
What speed are you feeding your stock at?

From contributor O:
Who's sharpening your cutters? I'd start there. The best bits/blades in the world can be ruined by a hack in an instant.

From contributor D:
I agree with contributor R on this one. It is a problem with the feed. Do you wax your top? A bare metal top will cause the material to stick to the shaper table and it will actually hop through the cutter, causing chatter marks. Also be sure you have plenty of downward pressure on your feeder, 1/4 inch or more.

From contributor A:
How old is this shaper? You checked the runout at the base. More importantly, what is the runout at the tip of the spindle? You lined up the spindle to the table. Did you clamp a ruler in the spindle to see if the spindle is mounted correctly? We typically take at least 3/32" off when fabricating door parts as well as most general millwork. This helps to prevent tearout. Do you have another shaper?

From contributor W:
Wax the fence too when you do the base. My money is on the wax solving the problem.

From the original questioner:
I wax the top and fence with Johnson paste wax and even tried feeding it by hand to see if it was the power feeder, but it did the same thing. I have tried varying the depth of cut to see if it just needed more wood to make a good cut. The cutters have never been sharpened; they're still new. The runout at the top of the spindle was only .002. Freeborn said it's possible the spindle might be messed up though, so I've got a new one coming today to try. Thanks for all the suggestions. They're all good things to be aware of

From contributor J:
Contributor R was talking about using an outboard, or trap fence instead of the factory fence. This can be as simple as a straight board clamped to the front of the table, spaced away from the cutter so that it controls the finished width. The rail/stile is run between this fence and the cutter with the feeder angled away from the cutter, towards the fence board. I've seen poorly attached pulleys on the spindle and motor cause vibration on light shapers.

From contributor R:
Yes, that's what I mean - contributor J explained it a little better. Clamp a board down, trapping the material between the fence and the clamped down board, snug but enough room for the material to slip between them. Don't angle the power feeder toward the cutter, let the cutter push the material towards the board that you clamped down. If any angle on the feeder, point it away from the cutter. You can hand feed or use a push stick. All the ideas that have been suggested are good, but you already tried them. Your material is bouncing at the cutter and that's all it is. If you fix it with any new parts or by tightening bolts, it won't be the new parts that fixed it, it will be luck, and will happen again when your material is slapping the cutter like an ace of spades in the spokes in a bike wheel.

From the original questioner:
So... Contributor R, are your fences still set so that they take off material with the cutter (i.e. like a jointer) or are they in line with each other? How much material do you take off when your door stock goes through the cutters?

From contributor E:
With an outboard fence there is no adjusting like with the stock fence. The material rides on a straight edge opposite the cutter. So it doesn't matter how much material you remove, you're still registering against a straight edge. For what it's worth, I remove the profile plus about 1/16". I find that to be a good setting for clean cuts.

Also, you mention you varied the depth of cut. Have you tried running the parts in 2 passes? One pass to take off the bulk of the cut (say 65-75%) and a secondary pass to finish the cut and give a cleaner finish? A full profile in a single pass using a smaller 3/4" cutter and a powerfeed may be too much for that machine to run comfortably?

I know there's an awful lot of those little shapers out there and guys love 'em, but I was not a big fan. I moved up to a Powermatic 27 which is much more powerful and carries a bigger 1-1/4" spindle, and I still find I'd like something bigger. I'd give the second pass a shot just to see if it helps.

From contributor R:
I run my fences in line. I had to have the complete assembly re-machined because Powermatic couldn't manufacture to my standards, but with the outboard fence, almost any fence will be okay, and no I don't, as some call it, "burn an 1/8th" simply because I don't like emptying the dust collector and if I removed any unnecessary material I would only be creating wood shavings. You stated you had a Delta 3 hp which is plenty of HP on 3/4'' thick stiles to shape one pass. If you set your fences in line and start out removing no material other than what is required to complete the profile with the outbound (I call outboard) fence, I am sure it will solve the problem.

From contributor Y:
Try Trewax instead of Johnson's. Lasts longer and is less oily. I also like to feed to an outside fence, just keep the clearance to the inside fence limited so the cutters can't accidentally take a big bite. Don't cant the feed too much into the fence. I'm not a fan of the light duty shapers. For what they cost new you can buy a good used production quality machine. There is a world of difference! We've got 7 shapers in the shop, all with feeds - great tools.

From contributor R:
Are the marks gone?

From the original questioner:
Yep, the marks are gone. Here's how I finally got rid of them. After replacing just about everything, trying Delta tech help, service center, Freeborn tools and finally my Delta dealer (who I have bought a lot of equipment from through the years), they allowed me to swap for a brand new machine exactly like my old one.

Guess what? No marks. Beautiful raised panels. They were wondering if maybe the old one had some cracks in the housing to the spindle, etc. But anyway, I'm happily making doors today. Thanks for all the great ideas.

From contributor L:
Nice ending to an all time bad story.