Problem with Delta 17-990x Drill Press

[Jim Peck]

I bought a Delta 17-990x drill press last week at a fire-sale price because it wasn't working properly. Got it cheap enough that even if I can't get it to work it won't be a big deal.

This model has a variable speed control--via a Reeves drive mechanism you can adjust the speed without moving belts from one pulley to another.

The motor appears to work fine; its shaft spins freely. The two shafts with the Reeves pulleys also turn freely.

The problem seems to be that the drive belt (far left of the screen in the video, going from the motor shaft to the shaft with the first Reeves pulley) isn't doing its job. Here's a video:



The belt on there looks to me like a standard automotive v-belt--perhaps the prior owner replaced the original belt with the wrong size or profile of belt and that's the entire problem.

In any event, like with many older Delta products the correct belt is not available for order from any of the online supply places I've been able to find. Hoping someone here will have some insight--either where to get a belt that will work or what the real problem is if you think I'm barking up the wrong tree. (Can I use a small link belt for the drive belt?)

Many thanks,

Jim

[Lee Schierer]

You can obtain the correct belt from ereplacements.com The correct belt will be critical for that continuously variable drive arrangement. Most likely the previous owner took something apart and left out the key and or set screw on the drive pulley. The bigger belt appears to be a Gates 1922V363 Bandless Multi-Speed Belt @ $65.00 each

[Bill Dufour]

The belt is not the problem. All the rotating parts are moving together with no obvious slip. There is something. wrong with the bearings somewhere the motor is stalling. First step is to remove the first drive belt and see if motor runs at full speed with no load. the jam a stick onto the pulley and see if motor can run under load.
I would suspect the reavees drive pulley shaft bushing is worn and the entire pulley cocks over and jams under load.
I would replace that power train with step pulleys and a three phase motor with VFD. That will be cheaper then resleeving and run quieter. You gain instant reverse, dynamic braking etc.
Bill D

On edit: watching again. does the motor stall or is the pulley slipping on the motor shaft? There is something blocking my view of the shaft end.

[Rob Charles]

Nice score based upon our description of the price you paid.

It is hard to tell from the video what is occurring. The audio suggests the motor is running, perhaps close to normal speed. However, the video indicates the (high/low) 1st Reeves pulley, the one on the left is not turning at the same speed as the motor. While I have not been into that portion of that model drill press, the parts diagram indicates the connection has both a key & set screws, it sounds as if the key or set screw in that connection has worn or slipped so that the motor shaft is spinning inside the reeves pulley.

It also appears that the 1st (small dia) reeves belt has taken a set (possibly from non-use. After you get the 1st reeves pulley problem fixed, if you find that the belts are slipping under load, two (2) springs on the center shaft maintain belt tension. Those springs do not appear to be the highest quality spring material. If the springs have been kept in compression, they take a set & no longer maintain proper belt tension. The springs are such poor quality that one can stretch them back out & it will work again for a while. If the drill press is left in the mode where the springs are at max. length (without looking at it, my memory is that it is in the high/high setting) it will work fine for quite a while. Replacement springs are readily available from McMaster/Carr.

If you need it, I think I have in my cabinet, a manual & parts list for that version, & can make you a copy. But, please know, it is not the greatest manual.

Good luck with it.

[Jim Peck]

Thanks to all for the comments, especially Bill and Rob. I've downloaded the manual from the web--as you suggest, Rob, it certainly leaves a lot to be desired. Amazingly, the manual doesn't even mention how to change the belts, as if the belts were expected to stay good forever! (Did they use some miracle rubber that would never wear out?)

Can I get to the pulley set screws (or change the lower drive belt, for that matter) without removing the central Reeves pulley? I can do that if necessary but would be much easier if there is another solution. Of course, if the springs are the problem as Rob suggested, I'll certainly have to do some dismantling.

I may not be able to get back to this repair for a few days but will post what happens when I do. When I had an old Jeep I used to participate in a Jeep forum. It was very helpful to go through post archives from many years in order to trouble-shoot problems (and old Jeeps always have problems!). So, I hope not only that I can fix the drill with the suggestions provided here, but that this thread can provide help to others who encounter similar issues in the future.

Jim

[Lee Schierer]

Can I get to the pulley set screws (or change the lower drive belt, for that matter) without removing the central Reeves pulley? I can do that if necessary but would be much easier if there is another solution. Of course, if the springs are the problem as Rob suggested, I'll certainly have to do some dismantling.

There is a key and key way in the lower half of the drive pulley. If the key is missing or sheared, which appears to be the case, you will need to remove the top half of the drive pulley assembly to replace the key. It appears that you can remove the cam and rod assembly for changing speeds and then the top half of the drive pulley should lift off.
drill.JPG

[Rob Charles]

It is not hard at all to disassemble the center Reeves pulley. I press down a bit, a pair of C-clip pliers & apart is comes. It is a bit harder putting it back together. A 2nd set of hands or clamps or other device to hold the springs in compression (often, several plastic wires ties on each spring holding it in compression does the trick. Once the C-clip is back on, simply cut the wire ties. Leave the tails on to make it easier to pull them out once cut). My memory is that the easiest starting point is in the speed setting where the spring is in maximum extension.

With the center pulley apart, the belts come off easy. With the lower belt off, disassembling the smaller Reeves pulley should be straight forward.

Also, it might be easier to pull the head of the post to set on a bench for easier access. If you have an overhead point, it is pretty straight forward. My memory is 2 set screws holding the head to the post.

IMHO, those are very nice drill presses and are well worth time time to invest to bring it back to condition. Hopefully, the motor shaft &/or Reeves bore is not damaged beyond reassembly or repair.

Good luck with it.
My guess is that the belts will come back to shape with some run time or if you put them over a suitable dia. mandrel to hold them close to round.

[Jim Peck]

Well, it's been a lot longer than I thought before I could get back to work on this project. I was finally able to tear it down on Saturday. There are a number of minor issues, but a couple of the parts are just flat broken and (via any online source I could locate--and I spent a few hours trying) unavailable.

1. The drive pulley on the motor shaft is a reeves pulley as well. The lower half of the drive pulley is worn next to where the key inserts to keep the pulley and motor shaft aligned. In this photo you can see (on the backside of the key slot) where the slot has been worn to somewhat of a "Y" shape. I can't think of any fix for this apart from replacing the part.
20190824_193808[1].jpg

2. Worse, perhaps, than #1 is the part Delta calls the "bearing cap" (part #196 in the chart Lee posted above). This is the point of contact between the speed adjustment arm and the Reeves drive pully assembly. When you move the arm, a cam rotates either pressing down the bearing cap or allowing it to lift, which adjusts the effective diameter of the Reeves drive pulley. As you can see in the photo below, the place on the bearing cap with the point of contact for the cam is broken through (that bit in the hole is hanging on by whatever the aluminium equivalent of a thread is).
20190826_164704[1].jpg

I can't find online a source for either of these parts, so I don't think this problem is repairable.

I'm giving thought to Bill's suggestion of replacing the various Reeves pulleys with standard, three-level pulleys and perhaps a VFD. I'd be interested in hearing if anyone has done something similar. And where I might obtain such pulleys.

Many thanks,

Jim

[Rob Charles]

That bites! Sorry to read your update.

I was using my 990X this evening & was reminder how much I like the ease & simplicity of quickly changing the speeds. Given your update, one day soon, I think I will verify the set screw tightness on the motor drive Reeves pulley & insert a delrin or similar wear strip on that bearing cap.

Ebay has a number of various size Reeves pulleys & new Reeves pulleys are available from several sources (ie. Master Power Transmission, etc.) Can any of those be adapted as a replacement?