Jet 20" Drill Press Repair Question

[Brian Kent]

Jet JDP-20MF.

This used drill press has made beautiful holes but has some vibration in the head. I thought it needed new belts. But today I changed to a slower speed and found the problem. The pulley assembly attached to the motor has a huge amount of wobble. The pulley assembly is held to the shaft with a socket set screw. I loosened it but could not easily move the pulley assembly off.

I would appreciate guidance on trouble-shooting this. The parts are listed here: http://www.misgroupinc.com/partfiles/m_354170.pdf (pg17).

I guess my first question is about leverage to get the pulley assembly off to check and see if the motor shaft itself is straight and to see if there are bearings I can replace. Do I need to get a gear puller?

Thanks in advance.

Brian Kent

[Myk Rian]

Did you look for a set screw under the first one?

[Brian Kent]

Did you look for a set screw under the first one?

As in two set screws on the one pulley?

[Bruce Page]

As in two set screws on the one pulley?
Brian, sometimes there will be a two setscrews in the same hole. The second one is installed to lock the first.

[Brian Kent]

OK, I got the pulley off.

First, the motor shaft runs true. Whew!

I see two possible problems. First, there is a deep scratch with a burr on the shaft. It is barely visible in these photos as a diagonal line on the right side of the shaft. Second, I have questions about the key. The blow up diagram of parts shows the key as a rectangle with rounded ends. This one shows a lot of wear, has a slope on one end. The key shows two separate places where the set screw has dug in.

I assume I should turn on the motor and rest a file on the shaft to get rid of the burr. Is this key OK?

Thanks. Brian

[Brian Kent]

With the burr removed from the shaft, the pulley - just resting in place - runs true.

Now I am not sure how to overcome gravity to hold that key in place and to keep it from sliding too far on the slope in the groove on the shaft. It fits loose so it will not just hold itself in place.

edit: And as I look at the parts diagram, I don't think there is supposed to be a slope in that slot on the shaft. If there is no slope, it would hold the key in place.

Sorry if I am using the wrong terms for these parts.

[Jerry Bruette]

I'm guessing that at one time the key either fell out or was taken out and the set screw was tightened into the key way. That could explain the deep scratch/gouge on the motor shaft. It's also possible that the motor has been replaced. The pictures are a little blury but the keyway in the pictures doesn't look like the type that would take a key that is rounded on one or both ends.

Does the keyway get shallower closer to the motor end bell? If it does you wouldn't need to round either end of your key. I would probably put a new key in if the old one shows any wear.

If you'd like to file the motor shaft do it very carefully and not under power. You'd run the risk of tapering the shaft or having the file get caught in the keyway and possiby you'd have pictures to show us of your new injury.

I'd also find a way to measure the inside diamater of the sheave to make sure it's not over size or egg shaped.

Jerry

[Brian Kent]

If the sheave is the pulley, the inside diameter is 61/64"
The shaft is also 61/64" using the same gauge.

The key slot in the pulley is 28/64" wide. The key is 25/64" wide. 3/64" of play.

I went to measure the key slot in the motor shaft and found another big problem. The slot is completely misshapen, I assume because of an undersized key rattling around in there for years. I hope these photos show it. I apologize for my cell phone camera quality.

I am now looking for a fix I can live with that does not include replacing the shaft. It is the original Jet 1.5 hp motor.

[ray hampton]

the keyway in the motor shaft and the key are made to fit snug so that the key will stay in place while the pulley are installed, if the fit between the keyways and the key are not close then the key and the keyways will get damaged when you start and stop the motor time after time, If the key got a slope on one end of the key, will you install the key before the pulley or after the pulley are install ?

[Jerry Bruette]

Brian,

You have what's known as a wallowed out keyway. The absolute best way to fix it would be to replace the motor, I know that's an expensive choice you'd rather not make. You could try a product called Loctite 660. It's made for repairing worn shafts and wallowed out keyways. I've never used any myself but the factory rep from Henkel...Loctite's parent company... assured us that it would work at the training seminar we had about two weeks ago.

If you try it be sure to clean the shaft good, use the reccommended primer and follow the directions closely. The Loctite products I have used are very good, but like I said I have no personal experience with 660.

Jerry

[Cary Falk]

Do you have access to a welder? I would either try to fill in the space and from with files or a dremel. You could also tack the key in place and clean it up wit a dremel. You really can't make it worse at this point. Epoxy cam to mind to fil the gap but I don't think it will hold up.

[ray hampton]

If the sheave is the pulley, the inside diameter is 61/64"
The shaft is also 61/64" using the same gauge.

The key slot in the pulley is 28/64" wide. The key is 25/64" wide. 3/64" of play.

I went to measure the key slot in the motor shaft and found another big problem. The slot is completely misshapen, I assume because of an undersized key rattling around in there for years. I hope these photos show it. I apologize for my cell phone camera quality.

I am now looking for a fix I can live with that does not include replacing the shaft. It is the original Jet 1.5 hp motor.

You can fix this keyway [motor shaft and pulley keyway] BUT IT WILL REQUIRE a lot of filing or scraping to renew the grooves and maybe file a blank of metal to make the key, if the grooves are even [motor and pulley] then either buy or make a new key,3/64 are close to 0.045 and in my opinion TOO MUCH free play

[Brian Kent]

Do you have access to a welder? I would either try to fill in the space and from with files or a dremel. You could also tack the key in place and clean it up wit a dremel. You really can't make it worse at this point. Epoxy cam to mind to fil the gap but I don't think it will hold up.

I can buy or make a key the width of the keyway in the pulley and square the whole keyway in the shaft. Then make another piece to fit the remaining area. If it is a good mechanical fit, the epoxy or JB weld may hold it in position long enough to install the pulleys. I am not too confident in my ability to do that cleanly, but as you said, I can't make it much worse.

How much is it to replace the motor?
Since I don't have the bucks today, I will try a fix and see how it works.

[Brian Kent]

Brian,

You have what's known as a wallowed out keyway. The absolute best way to fix it would be to replace the motor, I know that's an expensive choice you'd rather not make. You could try a product called Loctite 660. It's made for repairing worn shafts and wallowed out keyways. I've never used any myself but the factory rep from Henkel...Loctite's parent company... assured us that it would work at the training seminar we had about two weeks ago.

If you try it be sure to clean the shaft good, use the reccommended primer and follow the directions closely. The Loctite products I have used are very good, but like I said I have no personal experience with 660.

Jerry

This looks more reasonable to attempt, along with a key that fits the pulley better.

[Brian Kent]

Just a random thought…

When you stop to measure the thickness of a hot piece of metal while grinding, don't use plastic calipers.

That's all.

[John Coloccia]

Just a random thought…

When you stop to measure the thickness of a hot piece of metal while grinding, don't use plastic calipers.

That's all.

The corollary to this that is hot metal looks just like cold metal.

[Brian Kent]

Yup.

I ground the back of an old drill bit to the right size, set it in place with regular JB-Weld and spread some more into the void. Wiped the spindle surfaces off and set the pulley assembly in place to make sure it sets straight. Whatever I did that was stupid, I'm OK with that.

I'll let y'all know in 24 hours if it worked, and in the coming weeks or years I'll let you know if it held.

[ray hampton]

Have a good EASTER and report back Monday at the later

[Brian Kent]

Easter was great. My repair - not so much. It ran true when the belt was off, but with the belt on it immediately got loud and wobbly. I haven't thoroughly inspected it, but it looks like the top of the key is either pushed in or worn off. I may try another fix - try to remove the key, grind with a dremel 1.4" diamond wheel, and grind another key. Or I may replace the motor.

If I replace the motor…
What about a Harbor Freight motor for my light hobby use - not production.

Harbor Freight has a 1 hp (farm duty) and a 2 hp (compressor duty) that run at 1750 rpm like the Jet motor (which is 1.5 hp). They are reasonable at $149 for either one on a current sale. Would either of these work for the 20" Jet drill press?

Edit: the 1 hp has a 5/8" shaft. The 2 hp has a 7/8" shaft. The Jet has a 3/4" shaft.
Re-edit: I just discovered a 5/8" ID to 3/4" OD shaft adapter bearing, which would fit the 1 hp. Is 1 hp enough?

[Brian Kent]

I tried again with no changes, but put the belt on the bottom pulley on the motor side. That changed the leverage and it runs pretty good. That keeps me at faster speeds but most of my work is with smaller bits. I'll keep looking for the right permanent fix.

[Thomas Hotchkin]

Brain
You can get brass or steel shim stock at your local Napa auto parts store. Also I remember getting some over size key way stock some years ago I thing from Grainger. Or have a machine shop cut a new Woodruff key way on motor shaft. Good Luck Tom

[ray hampton]

Brain
You can get brass or steel shim stock at your local Napa auto parts store. Also I remember getting some over size key way stock some years ago I thing from Grainger. Or have a machine shop cut a new Woodruff key way on motor shaft. Good Luck Tom

how much will it cost to cut a new key way on the old motor

[Brian Kent]

how much will it cost to cut a new key way on the old motor

I haven't found a place to do that yet. Do I look under metal working?

[Jerry Bruette]

You'd look under machine shop to have keyway cut. You'll have to have the motor disassembled to cut the keyway.

If there's a data plate on the motor it might give you the frame number of the motor. That's what you'll need to know along with HP and RPM to replace the motor. That way the shaft diameter, length, keyway size, and bolt hole pattern for mounting will match what you have now. It'll make replacing the motor an easy job without further headaches.

Jerry

[ray hampton]

I haven't found a place to do that yet. Do I look under metal working?

maybe or machine shop, tool and die shops, motor repair shop, If they can not do the work for you maybe they can refer you to someone that will

[Gary Stamper]

If the multi-step pulley is wobbly, sounds like the bore in the pulley is wallowed out of shape. If the bore is loose on the motor shaft, no key will maintain trueness. The key is there to prevent the shaft from spinning inside the pulley bore. The shaft will keep it true. Measure both ends of the pulley in different orientations.

Gary S

[Brian Kent]

I followed leads from the local electric motor repair shops and got a couple of names in San Diego. I'll try again tomorrow when they open again.

Gary, that is a very helpful piece of information. I reached down with inside calipers and found a big problem. Near the opening of the pulley stack the hole is 3/4". Deeper in the hole is 1/16" larger, or .0625". I expect I should replace the pulley stack before going any further on the motor.

I ordered the new pulley.

[ray hampton]

I followed leads from the local electric motor repair shops and got a couple of names in San Diego. I'll try again tomorrow when they open again.

Gary, that is a very helpful piece of information. I reached down with inside calipers and found a big problem. Near the opening of the pulley stack the hole is 3/4". Deeper in the hole is 1/16" larger, or .0625". I expect I should replace the pulley stack before going any further on the motor.


I ordered the new pulley.

I hope that a new pulley solves your problem ,PLEASE recycle the old pulley if it is Aluminum

[Gary Stamper]

The aluminum pulley will wear out first so the shaft of the motor is most likely OK. The key should fit snugly in the key-way. If the one you removed from the drill press is loose it may have been replaced at one time with an incorrect one.When the new pulley arrives measure the key-way in it and the motor key-way. The two should be the same. If they are different sizes, the motor may have been replaced some time in the past. If they are different sizes, you have a couple alternatives. Replace the motor with one which has the correct key-way. They also make what is called a step key. It has a step on it to fit two different key sizes. McMaster-Carr has these as well as most industrial supply houses. If you go to mcmaster.com and search for step key stock, you'll find a number of sizes available.

Gary S

[Brian Kent]

Gary, check out post #8 of this thread. The keyway is really torn up. Right now I have a key in the post held in place with JB Weld. Not a good solution, but I could hardly make it worse.

[Gary Stamper]

In that case, the cost of repairing the key-way may be more than a new motor. I would be careful with the cheap Harbor Freight motors. It may say 1hp but the actual usable hp is lower. They will rate them at max start up hp. Which only happens for a second when the motor is turned on. The sustainable hp is the hp achieved during operation of the machine. On the cheap motor it may be as little as half the rated hp of the motor. A motor repair shop may be your best bet. The problem where I live is most of them don't want to work on anything other than 3 phase motors. No money in it for them. Cost of repair vs. cost of new. Good luck.

Gary S

[Brian Kent]

The new pulley stack arrived yesterday. Both the original and the replacement and the original are steel, not aluminum. It now runs smooth as silk. It is a testament to the mass of this drill press that I still could drill an even hole with so much wobble and vibration in the old worn motor pulley. It is also quieter and a steadier feel now.

Since the result was good and less expensive than I expected, I am replacing a couple of other parts - the hub assembly & handles (I had only one handle that was loose in the stripped out hub) and the depth scale bolt & nuts, because I realized that the nuts were not locking and were vibrating to a shallower depth than they were set.

All told, I paid $150 or $200 for the drill press and will have $150 in replacement parts, which is satisfying to me in a drill press that would cost me $999 if I bought it new.

[ray hampton]

just in time to build the high chair for the new son, congrats on both the drill press and the baby

[Brian Kent]

just in time to build the high chair for the new son, congrats on both the drill press and the baby

Right on, Ray.

[bob hertle]

Brian,

Chances are that the key never fit the shaft keyway properly. Consequently, it has been "working" since the press was new. I can't believe there isn't a member close to you that is also a well equipped (lathe and mill) metalworker who could help you out. If you were close to me (southwestern Ohio) I'd tell you to bring it over. Simple fix to cut a new keyway and (properly) fit a new key. More than likely the sheave (pulley) will also need to be bored and bushed and a new internal keyway broached. I'd post down in the metalworking section and see if I couldn't locate a Creeker near you who would be willing to help.

Regards
Bob

[Gary Stamper]

Brian,
Glad you resolved your problem with the drill press. It's a nice feeling to do a repair and have everything working as it should after the anxiety of it having a problem.

Gary S