Delta 46-700 series drive problem

[Dean Center]

The Delta 1440 Iron Bed in the shop at our local senior center started making noise today. When I checked under the hood, the spindle pulley moved fine, but when I changed the speed so the spindle pulleys moved apart, the belt got lots of slack. I found the fixed side of the motor pulley was loose and one of the set screws was not tight. After tightening the set screw, the motor pulley still did not move with changes in the spindle pulley width. I could not get the moveable side of the motor pulley to budge.

I have reviewed prior posts and understand that the zinc pulleys on these reeves drives are troublesome, but these seem straight and the lathe has been working well until today. I suspect the motor pulley has never been lubricated. Simplistically, it seems if I could move the fixed pulley closer to the motor, it would take up the slack and the moveable pulley would hopefully move to keep the belt tensioned.

I checked with our local turning guru, but he's recently had hip surgery and is still in rehab full time, so he can't come help. Considering that I have no experience with the innards of lathes, can anyone suggest how to proceed? Is there a reference that has the specs for how far apart the pulleys are supposed to be? And how to get them off and lubricated? And what silicone grease you recommend, Bill?

Thanks in advance and please phrase any instructions in step-by-step fashion that any dim witted 4 year old could understand? That's about my level.

Dean Center

 

[Bill Boehme]

The Delta 1440 Iron Bed in the shop at our local senior center started making noise today. When I checked under the hood, the spindle pulley moved fine, but when I changed the speed so the spindle pulleys moved apart, the belt got lots of slack. I found the fixed side of the motor pulley was loose and one of the set screws was not tight. After tightening the set screw, the motor pulley still did not move with changes in the spindle pulley width. I could not get the moveable side of the motor pulley to budge.

I have reviewed prior posts and understand that the zinc pulleys on these reeves drives are troublesome, but these seem straight and the lathe has been working well until today. I suspect the motor pulley has never been lubricated. Simplistically, it seems if I could move the fixed pulley closer to the motor, it would take up the slack and the moveable pulley would hopefully move to keep the belt tensioned.

I checked with our local turning guru, but he's recently had hip surgery and is still in rehab full time, so he can't come help. Considering that I have no experience with the innards of lathes, can anyone suggest how to proceed? Is there a reference that has the specs for how far apart the pulleys are supposed to be? And how to get them off and lubricated? And what silicone grease you recommend, Bill?

Thanks in advance and please phrase any instructions in step-by-step fashion that any dim witted 4 year old could understand? That's about my level.

Dean Center

Things can look fine from an external check, but there are a number of potential problem areas. It appears from what you said that it is just the motor variable pulley that is stuck.

However, remove the belt if you have not done so already and then check the movement of both the spindle pulley and the motor pulley.

First the spindle pulley -- it is just necessay to depress the plunger on the control lever to move it, but here are some checks to make:

• Holding the plunger down, move the control handle in both directions and at the same time look at the movement of the sliding half of the pulley. Do you see any slack between the control arm and pulley movement when you change directions? A slight amount of slop or free play in the would be OK, but it should be barely noticeable.
• If there is slop between the arm and pulley, look at the yoke assembly. The yoke is driven by a a round bar that sort of looks like a really large screw, but it is actually a rack gear which is driven by a pinon gear connected to the control arm. At the other side of the yoke is a smooth round rod called a follower that fits into a round hole in the headstock.The connections between the rack, yoke, and follower should be stiff and not flex as the control arm is moved from one direction to the other. However, my experience is that this area is one of the problem areas in the drive. The yoke on my lathe had a huge amount of flex at the connections of these three parts. the holes in the yoke where the rack and follower rods fit had a very loose fit and was only being held together by a roll pin at each of the connections which made the act more like hinges than rigid connections. Also, the hole for the follower was very much oversized. The reason that this is a problem is that there is a bearing in the yoke that fits the hub of the sliding half of the pulley.. If the yoke is loosey-goosey then that will cause the sliding half of the pulley to wobble and eventually crack the pulley at the hub. The wobbling motion also has an effect on how well it drives the motor pulley. As long as nothing is broken, you can look the other way for a while, but eventually something is going to break. I repaired mine by ordering a new yoke that was properly machined and then had a friend turn a follower rod on his metal lathe to give a better fit to the headstock hole. At least that problem can be fixed.
• While you are at it, make sure that there is clean grease on the spindle shaft so that things are not running dry. There is a dust boot around the spindle that you may need to move to peek underneath.
• At the same time check the square keystock on the spindle that serves as a guide for the movable pulley half. Sometime the keystock can rust and make it difficult for the pulley to slide.
• Finally, look at the belt. Belts on Reeves drive wear out much faster than they do on fixed pulleys -- and the belts on the Delta 1440 seem to wear out faster than they do on the average Reeves drive. If it is over a year old go ahead and replace it. Make sure that it is a belt designed for Reeves drives or order it from Delta. Reeves drives are supposed to use double wrapped belts, but most places can only supply a standard belt with raw edges. Raw edged belts wedge much tighter into the pulley groove which makes it harder to change speeds.

Now for the motor pulley -- that is the most troublesome area of the lathe drive, so I will jump right into it:

• You mentioned tightening the setscrews on the fixed half of the pulley. That seems to be a common problem. All of the vibration eventually loosens up the setscrews. I have used Loctite medium grade and it seems to works fairly well, but the setscrews will still eventually loosen. Just be very careful when tightening the setscrews -- remember that the pulleys are made of very soft die-cast zinc which cracks easily (don't ask me how I know this and I won't tell you any lies). 😀
• The keystock should also be checked. It is very interesting that when I bought my lathe, I found that the sliding half of the motor pulley would barely move. When I disassembled the pulley, I saw that the keystock was extremely rusty with very deep pits. It ws so bad that it could have passed for an old artifact from an ancient archeological dig. Anyway it should be bright and shiny with slightly chamfered edges so that the pulley slides smoothly on it.
• Just like the spindle, there should be an ample amount of clean grease on the motor shaft and keystock. I believe that the grease I have was R&D testing so I don't know if it is something that can be found at auto supply places. Any high quality wheel bearing grease should work just fine. I like the synthetic grease which does not seem to have the problem of the soap and oil separating and drying out. Anyway, the grease that I have was made by Chemtool and the container says High Performance grease. There is a sticker on the container with the following information -- Alpha 2000 HD2, Lot # 112586.
• The keyway on the movable half of the pulley tends to wear quickly due to the soft metal and vibration caused by all the sloppiness and wobble that exists in every part of the drive train. My experience is that it does not take very long before the keyway gets considerably enlarged and, of course, this is a run-away condition because the looser the fit, the more the vibration increases. I did numerous things to tighten up the fit of the keyway, but it was still like trying to make a silk purse out of a sows ear. Some "fixes" worked for quite a while, but the bottom line is that die cast zinc is not suitable for this application. It is often OK for fixed pulleys, but the metal bends and cracks in this application.
• Since the pulley seems to be stuck in your case, it sounds like things got dry (possibly the soap and oil separated). There is a spiral lubrication groove on the motor shaft -- the problem is that this groove has very sharp edges which can scuff the pulley bore (I also had that problem. The solution is to chamfer the edges of the groove a bit with small diamond files -- then polish the shaft to remove any traces of roughness. It is also possible that the keystock is rusty. (Did I mention that I know someone who had this problem?) The soft zinc in the keyway may have smeared and wedged things together. Replacement keystock is cheap. I bought five feet of oversized 4 mm keystock for about $10. I used oversized keystock because of the loose tolerances and fine-tuned the keystock with diamond sharpening stones.
• The thing that helped the most was to add a viscous damper to the spring to smooth out some of the vibration. After a lot of so-so solutions, I came up with one that worked reasonably well for about a year. It is fairly simple -- first I packed a lot of grease around the spring -- next, I cut some strips of Saran Wrap and wrapped it around the spring about a dozen or so times -- finally I secured the Saran Wrap boot with zip ties. One tie was placed on the pulley hub and the other was around a bushing between the spring and motor face. These surfaces are rather narrow, so it may take a few tries to get it to hold. Also, if there is too much grease in this home made damper, it will cause a blow out when the spring is compressed fully.
• Regarding your idea of moving the fixed side of the pulley closer to the motor face -- all that would accomplish would be to make the spindle run faster. All of the underlying root causes of the problem would still be there.

 

[Bill Boehme]

Also, how to remove the motor pulley set.

• Remove the setscrews.
• Some gentle tapping and wiggling may be needed to remove the fixed half of the pulley. It might even require substantial whacks, but be very careful -- this pulley is very easily deformed.
• You can't use a puller because it would bend the pulley.
• I went the "hail Mary" route when all other attempts failed -- I removed the motor from the lathe and holding my hand around the motor shaft between the motor face and pulleys and letting the motor hang vertically, I gave it a strong whack on the end of the motor shaft. Make certain that you have something soft for the motor to drop onto other than your toes. That got it loose, but I am sure that I didn't do any favors for the bearings. The problem was caused by burs along the spiral oil groove.
• Fix any problems.
• Replace any unrepairable damaged parts.
• Lubricate the shaft.
• Put it all back together. My recollection is that the fixed half of the pulley should be about 1/8 to 1/4 inch from the end of the shaft.
• Implement a viscous damper around the spring for best results to help reduce fluttering.

 

[Gretch Flo]

Thanks Bill

For your thoughtful and thorough explanations. Not that I understood any of this as I don't have issues and there are only so many holes in this old mind that new info can fit into. It's people like you that make this forum so helpful, Thanks again, Gretch

 

[Dean Center]

I agree with Gretch--thanks for the detailed and helpful response. The fixed half of the motor pulley is currently about 1/16" from the end of the shaft. My simple minded take is that it's slid so far out from the motor that the spring never gets compressed, so the pulley doesn't narrow to take up the slack in the belt. Should I be able to move the motor half of the pulley and compress the spring by hand? When I try this, it doesn't move at all. From your description, it sounds like the moveable half of the pulley is frozen. I can see a little dry grease and dust on the spring, but it may not have been lubricated since it was placed in the shop. There is still a boot on the spindle, but no sign of any grease on that end of the system otherwise.

Thanks again for the help. And expressing it at my level 😉

Dean Center

 

[Bill Boehme]

I agree with Gretch--thanks for the detailed and helpful response. The fixed half of the motor pulley is currently about 1/16" from the end of the shaft.

After thinking about it a bit, 1/16" sounds about right. Don't worry about the spring being slack -- it ain't gonna happen. When you remove the spring from the shaft, you will see that the spring is under a considerable amount of compression and not a chance in the world that the spring is slack. As I said earlier, DO NOT move the fixed half of the pulley any closer to the motor face than it already is. Otherwise, the lowest speed of the lathe will run faster than desired -- and there will be no benefit to performance. Furthermore, the speed range will be significantly reduced since the spring is already almost fully compressed at the low speed end.

Here is a shot of the motor pulley on my lathe showing its position on the motor shaft.



The headstock spindle and pulley was partly disassembled as I was overhauling the entire headstock.

EDIT: yes the sliding half of your pulley is stuck. The metal is probably galled in the center bore. If you can't force it off, you might need to saw it off or break it off.

 

[Dean Center]

More thanks, Bill. From the picture, I'd say my fixed pulley is less than half the distance from the end compared to yours. Also, please send me a set of those pulleys. I have enclosed a check for $19.99. 😉

Dean Center

 

[Bill Boehme]

More thanks, Bill. From the picture, I'd say my fixed pulley is less than half the distance from the end compared to yours. Also, please send me a set of those pulleys. I have enclosed a check for $19.99. 😉

Dean Center

The photo may be a bit confusing because it looks like the pulley is more than 1/8" from the end of the motor shaft. Actually, it is much closer, but there is a chamfer hat I turned on the end of the shaft that is creating an illusion of greater depth than what really exists. As long as one setscrew sits on top of the keystock and the pulley is not hanging out past the end of the shaft that is the ideal position because it give the drive the greatest speed range from slow to fast. As the fixed half of the pulley is moved in towards the motor face, the range of speeds gets compressed. You have been worrying about the spring being loose, but you will find that you must compress the spring quite a bit just to get the pulley onto the shaft.

 

[Scott Longberry]

Is this a newer Delta lathe or the older 46-700? The reason that I am asking is because I have a 46-700 and it looks nothing like Bill's picture of his headstock. If it is the older one, I happen to have a spare Reeve's pulley assembly for it.

Scott

 

[Dean Center]

Scott, I think it's the 715 and other than the hot rod pulleys Bill has, looks the same.

I finally got a moment at work to call tech support and was told that the fingers on the inside of the 2 halves of the pulley are supposed to interleave their full length, and that there is supposed to be a spring clip in a groove on the motor shaft on the outboard side of the fixed pulley. This is quite different that what we've been discussing and I wonder if he had the correct lathe in mind when he was telling me this. I'll get around to taking the pulley off later this week and can tell if there's a groove. If there is, it certainly answers the positioning question, though as Bill says, it might raise the minimum speed. The already too high slow speed is my biggest problem with this lathe.

All things considered, I think Bill's comment about the moveable half of the pulley being frozen is correct. Possibly in a position with the spring slightly compressed which would explain the large amount of slack.

 

[Bill Boehme]

Scott, I think it's the 715 and other than the hot rod pulleys Bill has, looks the same.

I finally got a moment at work to call tech support and was told that the fingers on the inside of the 2 halves of the pulley are supposed to interleave their full length, and that there is supposed to be a spring clip in a groove on the motor shaft on the outboard side of the fixed pulley. This is quite different that what we've been discussing and I wonder if he had the correct lathe in mind when he was telling me this. I'll get around to taking the pulley off later this week and can tell if there's a groove. If there is, it certainly answers the positioning question, though as Bill says, it might raise the minimum speed. The already too high slow speed is my biggest problem with this lathe.

Yes my lathe is the Delta 1440 Iron Bed Lathe (model 46-715). There was a later version that had some slight internal differences, but nothing major.

The reason that the motor pulley looks like it has been hot-rodded is because it has been hot-rodded. I turned the stock pulleys to true them up and then polished them with metal polish -- don't ask me why (it may be a pig, but it is a pretty pig).

I am glad that they mentioned the snap ring because it has been a few years since I last messed with it and I had forgotten about the snap ring. The snap ring serves two purposes, it keeps the pulley in the correct position and it also keeps the pulley from flying off the end of the shaft when the setscrews get loose (which they will do).

In order to remove the snap ring, you will need a good set of snap ring pliers (unless you enjoy tracking down flying snap rings when you try using a screwdriver, pocket knife, or el cheap-o snap-ring pliers). First, however, loosen both setscrews and push the fixed half of the pulley towards the motor face and then re-tighten the setscrews. Now, you will be able to access the snap ring. I learned the hard way that you remove the snap ring first and then loosen the setscrews, but first make sure that you have one hand snugly against the pulleys because the spring is under considerable compression. I did it the other way around and got hit in the gizzard with a pair of spring loaded pulleys as they came flying off the end of the motor shaft. Did I mention how strong the spring is and that it is under a lot of compression. They will make a nice round bruise on you if you do it wrong.

The way that Reeves pulleys work is sort of like finger joints in woodworking. The alternating slots enables the pulley halves to almost completely close together. BTW, you have to get the two halves of the pulley as a matched set because the keyway slot will not always properly line up with the two halves otherwise.

All things considered, I think Bill's comment about the moveable half of the pulley being frozen is correct. Possibly in a position with the spring slightly compressed which would explain the large amount of slack.

Well, OK I tried to warn you about the spring.

 

[Dean Center]

So you're saying I need a good pair of snap ring pliers and a Major League Catcher's outfit in addition to my face shield and apron? Can you get me a Texas Rangers autographed chest protector?

 

[Bill Boehme]

With the pulley stuck, it is hard to say how it might come off, but it would be worth your while to expect the worst that it might suddenly release and it could make a real pretty bruise.

Because of tonight's rain-out, you will need to wait until after tomorrow night to borrow the catcher's gear.

 

[Dean Center]

Well, simply, that went real well. The fixed pulley was out so far the snap ring was kind of embedded and when I got it off, it was broken. The moveable pulley was stuck, but a little Liquid Wrench and a few taps on the key and it came off. I cleaned all the gunk off (it looked like caked graphite), lightly smoothed with a scotchbrite pad, applied some marine grease (there's no silicone grease in our town), reassembled with a new snap ring, added several wraps of plastic over the well greased spring, and the pulley moved easily. NO excitement. Forewarned, I had the axle pointed in a safe direction, but it just slowly and stubbornly released the pulley. After checking the belt and applying some grease to the spindle pulley, I fired it up and what a difference. It now hums. I can quickly and easily change speeds without a floor jack. And the slowest speed is the same as before.

Thanks for walking me through this, Bill. Now I've got some confidence in tackling mechanical problems on this or the better lathe the future hopefully holds.

Dean Center

 

[Bill Boehme]

I am glad to hear that things went well. On one occasion, I also had a snap ring that was almost buried in the pulley after the setscrews had both gotten loose.

 

[Lyndal Anthony]

I have a couple of those horrible lathes in my high school shop. I am fixing the drive problem by retrofitting both lathes with variable spped motors from the new Penn State Industries 12" midi lathe. By the way I will never ever buy Delta anything again unless it is vintage/antique.

Lyndal

 

[Bill Boehme]

I have a couple of those horrible lathes in my high school shop. I am fixing the drive problem by retrofitting both lathes with variable spped motors from the new Penn State Industries 12" midi lathe. By the way I will never ever buy Delta anything again unless it is vintage/antique.

Lyndal

I sort of agreed with your feelings after my experience with the lathe as compared to a shop full of other Delta machines from a couple decades earlier. However after Pentair sold Delta/Porter Cable to B&D there seems to have been a shift towards better quality. At least the new Delta midi is really a nice lathe. I know several people who have them and I have turned on them several times.

The basic body of the 46-715 is fine, but the cheap variable speed drive was ... cheap. If I ever complete the project, I am also converting mine to fixed pulleys with electronic variable speed drive (the three-phase type as opposed to the Penn State DC motor).

 

[Dean Center]

I would also be concerned about the DC variable speed drives. The Delta is borderline for power with a 3/4 hp motor and stepping down to 1/2 DC won't improve that. If it works like the Jet DC variable speed, you only have full power at full rpm and that won't be worth the cost and effort, IMHO.

Bill,
Since you're investing in the upgrade, can we assume you think the bearings and other mechanical parts are of good quality, in addition to the bed/banjo/tailstock?

Dean

 

[Bill Boehme]

It uses standard bearings (6200 series, I believe), which are fine. The bearings in mine are nearly new and the spindle runs true so I am happly with it. I like the headstock lock and swivel features. One feature that I especially like is that the lathe uses really heavy duty T-slot nuts between the ways on the headstock, tailstock, and tool rest base. I don't know of any other mid range lathes that offer this. Most just have a bolt that goes through a very thick flat washer. The type with the washers seem to always hang when you are trying to move the tailstock or tool rest. Additionally, they are subject to backing off under load.

BTW, I have never had problem with insufficient power with the 3/4 HP motor, but one must remember that with a VS unit (either three-phase or DC), full power is only being developed when the motor is running at base speed. The bottom line is that is is smart to compensate for the loss of power at lower speeds by using a larger motor -- at least 1 HP.