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Need advise on Delta 31-250 Drum sander

2547 Views 10 Replies 6 Participants Last post by  Chris100
Couple years ago I got a Delta drum sander and used it with some success. Its big problem was the belt had no friction and you had to "help" the wood move through. It also seemed like the previous owner had the machine close to where they sprayed finish.

So, I decided to get a new conveyor belt, how bad could that be. Got the belt and installed it with procedure in an old Delta manual. First attempt positive was the wood fed as expected, no help required. The negative was/is the belt kept/keeps moving outboard (away from the motor side). The prior belt doesn't show this.

Tightening the adjustment screws didn't help. I tried outboard tighter, no improvement. I tried inboard tighter, no improvement. I tried moving the outboard bearing holder in two increments, no improvement (YouTube) which is the scribe mark in that picture.

I measured the belt and it is 49 7/8" with 1/32" difference at each end which I attribute to the measuring tape operator. The drive roller and idler roller measure the same when belt is tightened.

In trying to take out variables I replaced all of the fasteners involved with the adjustment since they were grade 5 or less and were giving me issues.

You can see from the pictures that the brass bearings are worn. I couldn't find any locally and not see them as root cause since tension/distance is on the inside of the egg shape.

The last picture show witness mark of where the belt used to track and where I have tried to use as a baseline.

Does anyone have a suggestion/experience? Any prior post links? (I did search first)


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Do you have the manual? I always found adjusting the tracking to be a tedious/aggravating chore, but it could be done following the manual. Here's what it says:

NOTE: With a new belt, it is not unusual for one side of the belt to be tighter than the other to make the belt track.
Frequent adjustments are normal for the first few hours use to allow for belt stretch. Adjustments to belt tracking can
also affect belt tension.
If belt (F) is tracking to the right, use the 1/8" T-handle hex wrench provided. Turn the right set screw (B) Fig. 17A
clockwise 1/4 turn or less.
If belt (F) is tracking to the left, use the 1/8" T-handle hex wrench provided. Turn the right set screw (B) Fig. 17A
counterclockwise 1/4 turn or less.
NOTE: Only adjust one side at a time and let the movement stabilize before adjusting again. Continue to tighten or
loosen this adjustment until the feed belt is tracking properly.

Couple of things that happened to me: tightening or loosening one side or the other willy-nilly is likely to stretch one side of the belt. Also, the adjustment of 1/4 turn advice is critical, the difference is literally in thousandths of an inch, so less is better.

If you do have the manual and followed their procedure, all I can say is keep at it (and good luck), it can be a pain.
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I have the manual and printed out those pages. Adjustment process is interesting to say the least. The fasteners holding the adjustment plates need to be flush but not clamping (DAMHIKT).

I'll try smaller fractions of turn, that may be the clue for me.

I just went out and tried Fred's insight and had no success, but did document another observation.

Even when the inboard (motor side) adjustment is loose and belt has a gap to the table on motor side, it doesn't matter how tight I turn the outboard adjustment to. The belt just keeps moving outboard past ends of the rollers. I cannot get it to track to the left!

You might try flipping the belt side to side (remove and remount to put the left side on the right). PITA I know, but it may help. It does sound to me like one side of the belt is stretched a little.
PITA for sure, but running out of options.

I'm baffled about the belt loose (gap to table) on the left then putting tension on the right and it not at least tracking straight or moving left. Even if I stretched the belt on one side it would seem I could adjust it to left with it being free on left.

Update: I flipped the PITA belt. Same exact thing, drifts right and cannot adjust left. It makes no sense since it worked with the worn out belt.
Same sander, same experience. Following manual…
No real update, but anecdotal info. I continue to run it and let it wear, maybe it will find a happy place or not. The problem replacement belt came in a Delta box and says Delta on it, I think it was old stock (vintage) because nobody has them.
I called another place and talked with a technician/engineer who had only seen Delta in years but aware of the tracking issue. So I ordered another belt, this time a Klingspor. The new belt isn't the heavy canvas of the Delta but a "polymer" back. I'm waiting for the replacement belt to really fail and then will change it out. Being a single person shop it isn't that easy. Simple & basic, just not easy.
Maybe try a new belt? Tracking is way tricky.
i had one and when putting on new conveyor belt it took me forever and a 12 pack or more to finally get it to track right, amazing how a scoush of a turn can make a huge difference, frustrating for sure, worse than trying to level up a large drum sander head that had to be loosened and reset, that was ugly.
rj in az
Same sander. Same scenario. Exact same issue with new belt. Solved it by releasing some tension on the right side roller mounting bolts on the motor side. I used a 9/16 wrench and gently loosened the two bolts. The roller moved back releasing tension. I retightened the bolts. I then started the belt and slightly tinkered with allen screws. Seems to be tracking like the old belt now.
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