Belt Deflection from platen?

[Martin Wasner]

I acquired an Oakley H5 edge sander a while back. The idler had rubber on it that was failing and I was advised that it could be removed. So I cut it off. Earlier today I was also replacing the carbon paper on the platen.

My question is, what is an ideal or correct amount of offset from the idler to the surface of the platen? Right now there is 2-1/4" of difference, I feel like that is going to wear that carbon paper pretty aggressively.

I don't know why the picture is rotated strangely.

[M Toupin]

Martin, It's been a while since I've seen a H5 in the flesh, but it sure looks like the roller is way under size. IIRC the drum should roughly be the same dia as the platen thickness with very little lead in angle between the drum and platen. That drum arbor looks way too clean, are you sure it's original or at least OEM sized?
Mike

[Keith Weber]

Martin,

I'm on the other side of the planet right now, so I can't access my Oakley to make any measurements, but IMO you have way too much of a platen overhang to that roller. I can't recall how much offset I have on mine, but it's probably in the neighborhood of 1/8" in each end. Too much overhang is going to give you two problems. First, you're going to wear through the platen material a lot faster at that edge, and secondly the belt going over that bend is going to have a bit of inertia when the belt is running, so it run slightly off the platen for a short distance (depending on the tension you use -- less tension = more pull away from the platen). It won't sand quite as flat near the edge as it would if you had a very slight overhang. It's also harder on the belt.

I like to have just enough overhang that the belt keeps positive contact with the platen, and no more. Your roller looks a lot smaller than mine, too, but you should be able to bring the ends of the platen and the tables inwards on that end to compensate.

Oakley.jpg

[Darcy Warner]

I know for a fact that that sander shipped from Oakley with an aluminum idler pulley and I believe they said 4" diameter on that. I would have to check what it is on my mattison and my EC 112.

[Larry Copas]

Smooth transition with a 3 1/2" diameter idler. Their is a shop made block behind the idler for some reason.

My machine came with the graphite glued to the platen. I would guess they used contact cement. In any case I've not had any trouble with it. When its time I'll probably replace the same way.

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[Martin Wasner]

I know for a fact that that sander shipped from Oakley with an aluminum idler pulley and I believe they said 4" diameter on that. I would have to check what it is on my mattison and my EC 112.

I just think the platens need to be adjusted in. I should've looked at my Ritter before I sold it and see what the offset on that was.


Larry, I stuck my new graphite cloth on with contact cement, I still used the clamps at the ends, it's just the easiest way to do it I think. Buy 10" material, let it hang over the top a bit, and your last step you just knife it off flush with the top of the platen..

[Martin Wasner]

The idler is 5" in diameter.

I adjusted the platens in, which while not difficult, was kind of a fiddly pain in the rear. I think what I really need to do is pull them out entirely make sure all the seating surfaces are clean and smear a little grease on them. Cleaning up the threads in the clamping posts and lubing them would be a good idea as well. I'm sure it would've made it easier and better had I done it correctly, I just don't have the time to screw around with it.

I went with the platen about 5/8" off of both the drive and idler pulleys. Why 5/8"? It just looked right going off of the approach angles that are ground into the platens. It sounds a little better, the belt tension doesn't have to be as extreme, which also means the tracking isn't quite as twitchy as it was before. Glad I posted something, it just didn't seem correct the way it was.


Larry, I should've added, the contact cement really only helps with keeping the center from sagging on the graphite over time. Everything else it just makes it a pain in the rear when mounting it. My old one, cleaning up the old contact cement was pretty easy. I just hit it with a wire wheel in an angle grinder to remove it. I actually wire wheeled this one and cleaned the surface with 3M adhesive remover/cleaner before rattle canning on Super77 to stick it down.









This forum really needs a way to attach pictures with less steps, and auto hotlink them into the text so you can see them on the mobile version. Once you do it a few times, it's not hard. Just a lot of steps.