Hamilton Sensitive Drill Press pulley replacement.

[Bakafish]

I have taken a short video with commentary.

I essentially say this in the video, but from what I can tell it seems that the raised bump may go all the way across the inside of the idler wheel, and fits into a notch cut all the way across the bearing. Is it possible that the idler is press-fit onto the bearing, and the raised area w/ the notch is so it's locked into place from slipping when rotating? Looking at images of the bearing online, there are definitely no notches cut into it, so I assume it must serve some purpose, if not the one above.

The bearing itself seems to have some wobble, which I guess may be why the pulley worked it's way loose or was damaged ?
Originally I just thought that it was only the idler wheel wobbling on the bearing, but I was wrong. with the cap off, pressing gently on the outside ring of the bearing, it has play. The other side does not.

Granted, the idler wheel does still have play in addition to the bottom ring of the bearing.

One other question, what grease would you recommend I apply to the bearing? A brand or viscosity to look for?

& thank ya'll for being patient with me here; a bit new to this type of stuff.

I've never seen a keyway cut across a bearing race, and those bearings don't seem to have one. It's not what I would consider good practice, and I doubt that's what we are seeing there. The purpose of the raised area is a bit of a mystery to me, you would never want something like that in a concentric bore as all it would do is distort the idler or make it off center. The only thing I can think of is they end just outside the edge of the bearing seat area and were there to help retain the bearing in the bore, to keep the idler from slipping from side to side like the bad one is doing, you would basically press the bearing past it, and it locks the bearing in place. Crude, but effective for some period of time. If/when you fully disassemble them it may become clear what they are.

With one bearing exhibiting clear signs of wear (deep groove bearings should not noticeably wobble), disassembly and replacement of the bearings is warranted. A three armed bearing puller is recommended, and you should do everything possible to distribute the force equally across the backside of the idler wheel if you want to minimize the chances of damage. The puller is naturally going to grab on the weak lip of the idler, and that's very likely to break. So a large steel washer (or 2!) with the same or slightly larger diameter with a slot cut so it can be slid over the shaft, or some similar reinforcement would be suggested.

I made a model based off of the drawings, scaled to the known dimensions of that bearing that could likely serve as an effective replacement if you want it. You can have it 3D printed out of nylon in CN/US and shipped to you fairly reasonably. The testimony from actual users that the wear isn't a big deal reenforces my opinion that just carefully swapping the bearings (agree with others that fully shielded rubber seal type bearings make the most sense) and using the appropriate Loctite (seriously there are a lot of different ones, pay the money for the correct one for the task) are likely the best solution overall. You can always make or find new idlers down the road if there's a problem, although you should see if you can find replacements since you will have it apart anyway. Regreasing the existing bearings is moot as they are clearly damaged, but normal type 2 or 3 lithium bearing grease is fine for that application.

If you are going to go through the effort of making new wheels, then replacing the shaft so it can have proper retainers instead of the (apparent) press fit would be worth considering as well.

 

[noynac]

I've never seen a keyway cut across a bearing race, and those bearings don't seem to have one. It's not what I would consider good practice, and I doubt that's what we are seeing there. The purpose of the raised area is a bit of a mystery to me, you would never want something like that in a concentric bore as all it would do is distort the idler or make it off center. The only thing I can think of is they end just outside the edge of the bearing seat area and were there to help retain the bearing in the bore, to keep the idler from slipping from side to side like the bad one is doing, you would basically press the bearing past it, and it locks the bearing in place. Crude, but effective for some period of time. If/when you fully disassemble them it may become clear what they are.

With one bearing exhibiting clear signs of wear (deep groove bearings should not noticeably wobble), disassembly and replacement of the bearings is warranted. A three armed bearing puller is recommended, and you should do everything possible to distribute the force equally across the backside of the idler wheel if you want to minimize the chances of damage. The puller is naturally going to grab on the weak lip of the idler, and that's very likely to break. So a large steel washer (or 2!) with the same or slightly larger diameter with a slot cut so it can be slid over the shaft, or some similar reinforcement would be suggested.

I made a model based off of the drawings, scaled to the known dimensions of that bearing that could likely serve as an effective replacement if you want it. You can have it 3D printed out of nylon in CN/US and shipped to you fairly reasonably. The testimony from actual users that the wear isn't a big deal reenforces my opinion that just carefully swapping the bearings (agree with others that fully shielded rubber seal type bearings make the most sense) and using the appropriate Loctite (seriously there are a lot of different ones, pay the money for the correct one for the task) are likely the best solution overall. You can always make or find new idlers down the road if there's a problem, although you should see if you can find replacements since you will have it apart anyway. Regreasing the existing bearings is moot as they are clearly damaged, but normal type 2 or 3 lithium bearing grease is fine for that application.

If you are going to go through the effort of making new wheels, then replacing the shaft so it can have proper retainers instead of the (apparent) press fit would be worth considering as well.

I am willing to purchase a tool and attempt to remove and replace the bearing / have a company print new wheel. When it comes to replacing the shaft to have proper retainers, as nice as that would be, is likely out of my scope at the moment. I could probably try that later on next year.

Just to make sure I understand, you are saying to use loctite when press-fitting the wheel onto the bearing, or when pressing the bearing onto the shaft?
What would your suggestion be for the best way to press the bearing onto the shaft?

Whether it is just tight / stuck / etc., the shaft seemed quite well in-place even with the center set screw removed. Guess I'd need to press or hammer it out?
Given that, it would still be possible to press the bearing on without removing the shaft?

The entire idler assembly comes off (I have already taken it off once).
I wonder if I could remove the bearing that is damaged, get a small gauge block that's around the size of the shaft to place onto the other side, and then put it into a vise and close it. (my thinking being that the vise jaws would hit the wheel, so I need a spacer).

I'm sure there's a specific press that would work best, but it would probably be out of my budget.

If something DIY like this is likely to fail, then I can just wait until next year and use it as-is for now.

I see very cheap bearing removal kits such as this from amazon that can be here in 2 days.

 

[Rob F.]

I think if you grease the bearings, use just about any grease that you have, they will be fine for a very long time.The only other thing I would have to do is loctite the loose bearing onto the pulley and shaft, you may not even need the snap ring if the groove is bad.
This should get you a long ways down the road when you should have built up more skills and knowledge to re evaluate this then, that might be years or even decades from now, certainly no next week.

 

[Bakafish]

I am willing to purchase a tool and attempt to remove and replace the bearing / have a company print new wheel. When it comes to replacing the shaft to have proper retainers, as nice as that would be, is likely out of my scope at the moment. I could probably try that later on next year.

The set screw likely raised a burr along with years of slow corrosion. If the idlers were removed it would likely tap out with little trouble, but I'm a perfectionist, you can easily get by without replacing it. It's worked so far.

Just to make sure I understand, you are saying to use loctite when press-fitting the wheel onto the bearing, or when pressing the bearing onto the shaft?

Because both are using 'press fits' then retaining compound would help both. The bearing to shaft fit is presumably pretty tight now, but with a new bearing and cleaning, there's going to be more clearance and the Loctite will ensure the bearing won't slip.

What would your suggestion be for the best way to press the bearing onto the shaft?

A small hand press with the assembly removed. I'm getting the feeling you are at the beginning of your journey and likely don't have a lot of tools yet, so I worry you may be tempted to improvise. It's very easy to make things worse, even with the right tools and knowledge. Always do the least required to solve the issue and minimize damage.

Whether it is just tight / stuck / etc., the shaft seemed quite well in-place even with the center set screw removed. Guess I'd need to press or hammer it out?
Given that, it would still be possible to press the bearing on without removing the shaft?

Yes, with a standard benchtop hand press (not as expensive as you might think in the US) it should be able to seat both new bearings with the existing shaft in place without much effort. When pressing a bearing it is really important to not put force on the balls, so you would apply the force to the inner race when pressing it on the shaft. Most people use an appropriately sized socket for this, which is a good hack for a home shop.

The entire idler assembly comes off (I have already taken it off once).
I wonder if I could remove the bearing that is damaged, get a small gauge block that's around the size of the shaft to place onto the other side, and then put it into a vise and close it. (my thinking being that the vise jaws would hit the wheel, so I need a spacer).

Gauge blocks are to be used for measurement, don't use them as tools. Vices are also not really ideal for pressing something this long, they don't apply loads very evenly and there are many ways to get yourself in trouble.

I'm sure there's a specific press that would work best, but it would probably be out of my budget.

As I said, cheaper than you probably think. An irreplaceable tool if you intend to collect these older machines that often need bearing replacement. But there are likely shops around you that would happily press these bearings in for a small fee.

If something DIY like this is likely to fail, then I can just wait until next year and use it as-is for now.

Waiting and planning a strategy is always good, just make sure the current issues don't cause further irreversible damage. The bearing sliding around inside that idler is bad, it will wear it in a way that could make it unusable, so dealing with that needs to be a priority if you intend to use this. I'd also replace that belt with a smooth (abrasive free) belt to prevent further wear.

I see very cheap bearing removal kits such as this from amazon that can be here in 2 days.

A kit like this has the items necessary to remove the bearing, those bearing splitters can be used as the backing plate to support the fragile idler. I'm not a fan of cheap tools, but I'm better off than most. Make sure you have a plan and everything else you need (replacement bearings, retaining compound and a way to press them back on.) Take your time, clean meticulously, do your research.

 

[animal12]

I'm wondering if there's a missing snap ring on the inside of the pulley that slides back & forth ?
animal

 

[noynac]

I'm wondering if there's a missing snap ring on the inside of the pulley that slides back & forth ?
animal

I don't think so, because there is no snap ring on the good bearing on the other side either.

A small hand press with the assembly removed. I'm getting the feeling you are at the beginning of your journey and likely don't have a lot of tools yet, so I worry you may be tempted to improvise. It's very easy to make things worse, even with the right tools and knowledge. Always do the least required to solve the issue and minimize damage.

Yes, with a standard benchtop hand press (not as expensive as you might think in the US) it should be able to seat both new bearings with the existing shaft in place without much effort. When pressing a bearing it is really important to not put force on the balls, so you would apply the force to the inner race when pressing it on the shaft. Most people use an appropriately sized socket for this, which is a good hack for a home shop.

I see arbor presses and hydraulic presses. I estimate I'd need around 5.5" minimum working distance vertically in order to press a new bearing on awhile supporting the shaft from the other side. So realistically more around 6" - 6.5" to be safe with a low profile socket.
The arbor press I see that offer this much working distance are 3 ton presses at around $260 cheapest. Honestly, I probably can't get that. School really drains my income.
I see 6 ton H-frame hydraulic presses with around 10" working distance for $100~, which is plenty of height at a price that won't hurt too bad.
Though I am kind of on edge wondering if hydraulic is a good way to go. I see videos of hydraulic presses being used for large bearings in car parts, but with something this small, would it be fine?
More-so I am thinking that I won't be able to "feel" if it's fitting "right" so-to-speak. Of course, I have no experience with this, so I cannot backup that thinking.
But I wouldn't want to damage anything in the process and cause more trouble for myself.

If hydraulic is not ideal, I can look around shops, though I am not really sure what types of shops would offer this service.

I made a model based off of the drawings, scaled to the known dimensions of that bearing that could likely serve as an effective replacement if you want it. You can have it 3D printed out of nylon in CN/US and shipped to you fairly reasonably.

That would be much appreciated. Yes, I would like to have the model.

edit: it looks like 6200-2Z shielded bearings are basically the same as Fafnir 200KD.
Same dimension, both ABEC1, same internal clearance, etc. and are only $5/each new. Bearing removal tool and some washers is around $50. and a nylon 3D print really shouldn't be too much either, loctite is maybe $20~.
I feel like I am close to being able to make this happen, just need a cheap way to press-fit it all together.... That's a scary word, cheap.

edit 2: tried looking for local used arbor presses. Found a few but they are basically the same price as just buying new.

 

[Bakafish]

Hydraulic press should be fine, as long as everything is straight and clean, feel shouldn't be a factor. Again, with that assembly being so easily detached from the machine, a local auto shop will do it for a six-pack or less. They have the pullers as well. Friends with tools (you don't have) are worth making.



This is a simplified model of the idler based on the PDF drawing, it is designed for a 30mm x 1.2mm snap ring. These forums do not allow me to directly attach 3D files so it is embedded in the image above. To extract the embedded 3D file, download the jpeg image to your computer and use WINZIP or WINRAR to open the jpeg and inside there will be the STL file 3D model of this idler.

I recommended rubber sealed bearings, metal shields will work, but rubber is less susceptible to dust and dirt. Using the more common 6200 series bearings is fine. When you have it made, professional 3D printing places (PCBway?) have various printing options you can choose, I believe using SLS (Selective Laser Sintering) with Nylon (or Glass fiber reinforced Nylon) are going to give you the best results.

I have no idea how expensive (~$15 to $30 each?) or dimensionally accurate the parts will be, I make my own stuff and I can just reprint if it comes out wrong. Double check the dimensions with your existing parts, use Onshape or some other 3D app to make any changes you see fit. I take zero responsibility unless they work out great

Good luck!

 

[noynac]

I've never seen a keyway cut across a bearing race, and those bearings don't seem to have one. It's not what I would consider good practice, and I doubt that's what we are seeing there. The purpose of the raised area is a bit of a mystery to me, you would never want something like that in a concentric bore as all it would do is distort the idler or make it off center. The only thing I can think of is they end just outside the edge of the bearing seat area and were there to help retain the bearing in the bore, to keep the idler from slipping from side to side like the bad one is doing, you would basically press the bearing past it, and it locks the bearing in place. Crude, but effective for some period of time. If/when you fully disassemble them it may become clear what they are.

I'll likely make one last update to this thread after this one. Once everything is fully completed.

I thought I would share my findings after removing the bearing though.

 

[Bakafish]

Good work getting it pulled. That raised key in the idler bore, and the crudely hand ground keyway in the bearing race is horrifying. Grinding hardened metal next to an open bearing is a bad idea, weakening the race in a single point is likely going to distort it as well. This isn't high load or precision, but what you are seeing there is a pretty ugly hack. They likely had few other options back then, but from the drawings of the presumably older variant that showed best practices retainers, this is cost cutting madness. Although it occurs to me that it may have been a 'wartime' machine, so I may be being overly harsh.

If you are going to reuse the old wheel, I would (after deep cleaning :-) ) carefully shave off that lip so it doesn't interfere with concentricity and fit, and use the modern solution of Loctite to retain the bearing.

 

[noynac]

I got a motorcycle mod shop to press the bearings for $50. Also bought some round belt and put that on there. Got the wheels printed from Jawstec with nylon12, and then pressed those in myself with a watch crystal press.
All is working good now. Thanks everyone!