Powermatic 160 planer bed leveling problem

I am working on my planer, which came partly in pieces. Today I was making the bed parallel to the head, setting roller heights, etc.

I'm using a Powermatic gauge, a long lever and spring deal that has about +/-1/32 travel. It's about 8" long. I made the bed parallel to the blade, set the infeed roller parallel and height. I went to work on the chip breaker and decided it would be easier from the other side. When I changed sides, I don't remember if I adjusted height or not.

When I got to the other side, the planer blade was no longer parallel, off a little less than 1/64". This was pretty alarming, so I went back to where I started--this was also off. I started over and it looks like when I adjust the bed height the parallelism changes.

The only thing I've been able to come up with is that if the bevel gears in the up/down mechanism aren't snug, maybe this would happen.

Any help will be greatly appreciated.

Thanks,
Steve

I'm not sure about your problem, but the gents over at owwm.org sure do know their old American iron inside and out!

Thanks. I went looking for that forum and discovered that I didn't actually have it bookmarked. I was also unable to find it, not remembering the name.
I'll give them a try.

It turns out that I've got a problem at owwm. I did have a login (according to Firefox), just hadn't bookmarked it. Tried logging in, no dice, no such user (not a password complaint). Same story when I said I forgot my password. So I went to register with the same email address. Address (same as login) already in use.

OK, so next step is to wave the flag to the admins for help. You cannot do this without logging in....catch 22. I guess I need to register with a different email address.

Steve

Powermatic used to supply a little book of calibration instructions if you called them and asked. That was 10-12 years ago, so they may have stopped the practice by now.

You are correct about the gears, I've had this problem with my PM-100. Unfortunately for me, I didn't catch it until I'd done some planing. I'd have to go look at the machine to be 100% sure, but I believe the problem is that you have to set the bed to parallel the head when the gear backlash on the raising mechanism is fully taken up moving upwards. If you don't do this, one side will kind of lag behind taking up the gear backlash, causing it to be lower than the other side - I seem to remember that the gear sets move in opposition to each other.

Steve,
This probably has nothing to do with your issue, but years ago a friend of mine bought a new Powermatic planer and couldn't get the bed and knives to stay parallel, repeating the setup process several times with no improvement in his results once he'd raised the bed back to working height (the boards ended up tapered across their width, like siding); finally he inspected the raising screws and noticed that the threads were of slightly different pitches, making one side of the bed raise faster than the other. Powermatic sent him a new screw (or maybe a matched pair), but offered no explanation how that screwup happened.