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Thickness inconsistencies

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Forum topic by Fiddy posted 11-08-2020 10:37 AM 438 views 0 times favorited 8 replies Add to Favorites Watch
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Fiddy

230 posts in 2318 days


11-08-2020 10:37 AM

So I’ve procrastinated spending the time to ho over a used Jet 20” I picked up some months ago. I know the previous owner had it set up poorly, but again, time has been tight so have managed to use it as is. Recently a grabbed a very lightly used 19-38 for a great deal on CL and I was milling up some hard maple for a cutting board. In making the first one, it had me confused at glue up.

Process was, milled at jointer, planed and ripper before sending each peice (face grain) through DS. Few passes on each face to help eliminate snipe etc.

First glue up and I have spots that would not pull in, even with all my cabinet clamps. Making a second one last night, I decided to take some time on the drum sander to ensure I got all the snipe and any other inconsistencies left from my planer. I took some time testing pieces (face to face) and I saw my issue. There’s simply some inconsistent thicknesses on these boards.

To be clear, my issue is not left to right, but instead along the length. Basically snipe, but at random points, not consistent across various boards.

My first thought/question – are my issues from planer translated to DS?

Somewhat of a ramble above, but any questions and or thoughts – let me know. I’m planning on sucking it up and going over my planer, but would welcome any suggestions.


8 replies so far

View Redoak49's profile

Redoak49

5091 posts in 2996 days


#1 posted 11-08-2020 11:40 AM

This is easy to figure out. Get your caliper out and measure each piece along its length. Do this for the planer and drum sander.

I set up my planers this way to minimize snipe. I have a Supermax 16/32 and was careful to set it up with the drum parallel to the bed and also adjusted the hold down bars properly. With time and effort, you can get it working properly.

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sras

5867 posts in 4137 days


#2 posted 11-08-2020 04:22 PM

Your description sounds like the board is stalling/slowing as it travels through the sander.

I have found that if the board stalls the drum will take a deeper bite.

A couple things to check:

- Make sure you are not taking too much off in each pass. Ideally a sander depth is set to remove a layer that is less than the size of the grit.

- Make sure the transport belt has enough tension. Usually this is not an issue but worth checking

-- Steve - Impatience is Expensive

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Rich

6525 posts in 1597 days


#3 posted 11-08-2020 04:37 PM

My first step would be to isolate the source of the unevenness. Check the boards as soon as they come off the planer. If that’s OK, then the problem is with the drum sander.

Additionally, even if the planer was giving an uneven surface, the drum sander would level that out. That leads me to believe the issue might lie with the sander. Is the head mounted securely?

-- Half of what we read or hear about finishing is right. We just don’t know which half! — Bob Flexner

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jkm312

74 posts in 411 days


#4 posted 11-08-2020 04:52 PM

I would first make sure the knives in the planer are set properly, all set at the same height. Make sure the edges measure the same after coming out of the planer. You will always get waves the same as the depth of cut you take because the knives can only be tangent at one point in the circular rotation they make relative to the board being planed.

Is the drum and feed rollers on the DS clean? No build up of sanding dust, pitch/sap from the stock being run thru under the belt?

If the above is correct, then +1 on what Seve is talking about.

When you run the test boards thru are you keeping them in proper orientation between the planer and DS? If you are turning them 180 degrees, then that would make it harder to pinpoint the problem area.

All of our machines get knocked out of adjustment a bit during normal operations over time. Eventually they all have to be recalibrated. It’s just a day of patience with your game face on and staying with it. Get out the manuals and go step by step. The first time you learn a lot about the equipment, then it is easier the next time.

View hcbph_1's profile

hcbph_1

92 posts in 322 days


#5 posted 11-08-2020 06:00 PM

I’m not familiar with that planer etc, but here’s a thought. If a machine has an infeed or outfeed table and they aren’t perfectly level, the board will rise or drop as it goes through the machine.

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Rich

6525 posts in 1597 days


#6 posted 11-08-2020 06:30 PM


If a machine has an infeed or outfeed table and they aren t perfectly level, the board will rise or drop as it goes through the machine.

- hcbph_1

That’s what feed rollers are for. They keep the board flat as it passes through the planer. They are so effective in fact, that they prevent defects like cupping from being removed by the planer because they press it flat, which removes the cup during the cut. The result is a thinner, but still cupped, board.

If you doubt their downward force, try switching the planer off halfway through and try to pull the board free.

-- Half of what we read or hear about finishing is right. We just don’t know which half! — Bob Flexner

View Redoak49's profile

Redoak49

5091 posts in 2996 days


#7 posted 11-08-2020 06:59 PM

This is a straight forward troubleshooting. Do one machine at a time.

Run a board thru the planer and measure the thickness along the length. Instead of guessing what might be wrong, use actual data to define the problem. That should help pinpoint the planer issues.

Once you have the planer fixed, you do the same for the drum sander. Trying to troubleshoot something that goes thru two processes complicated getting it figured out.

View Fiddy's profile

Fiddy

230 posts in 2318 days


#8 posted 11-08-2020 07:45 PM

So I think Steve nailed it – I spent some time with a single, wide board and went through the steps. Definitely some small issues with the planer, especially front to back, length of the board. Small but consistent differences that were replicated. Left to right, pretty dead on for the planer. I measured with calipers and marked each 4 corners.

I decided to try and move forward with my laminations on the drum sander and it did even things out, but exactly what Steve said I saw happened to me, whenever a board would get “hung up” I paid close attention and that board once ran and each had an irregularity. I tried to lighten up the cut and seemed to help. Last thing, I was ganging up 6 or so boards – I opted not to do that and seemed to help a lot. In hindsight I would’ve been much better off leaving wide for drum sander and then ripping down.

Anyway, I do need to get a day spent on my planer, but at this time I’m fairly confident the DS issues were isolated to the stock pausing.

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