Thread: Changing the top quill bearing to a taper one on a HM52

Hi CJ,
Your down feed casting looks like it's been machined, which is a lot better than how most come. Since I bought one I have looked at anything posted about these mills and it seems they vary a lot.

With the bearing carrier you will have to drill a large hole in the casing and drill and tap 3 holes in from the back of the casting. The bearing carrier would be like I posted in post 97, Something like this



For grease just your standard wheel bearing grease is fine, and is what I was recommended.

With SKF bearing, the last time I was over there he told me they are setting up a plant in China under there quality control, so there will be SKF bearings with China on them soon.

Dave

Cool thanks. I'll try that fix for sure. To answer the other question from the show me your mill thread, the Kurt is authentic. It has the serial number riveted in on the side with the Kurt emblem etc., its an angular vise. Did you also mention earlier that you tapped the spindle with a soft face hammer to remove it from the quill housing? And how did you remove the pulley bearings? I got another quote from an SKF dealer and I'm at $163 now. I'm going to barter a little and see where that gets me . I'm new to machining but I do know a thing or two about bargaining. Will post more pics as I go along and I'll post some of the little tools I've made as well. As always, thanks!
-cj

When I had a second look I thought it might be a original Kurt, because the base casting doesn't go around the back like mine.

Thats the way I removed my spindle, I think I used a block of aluminium on the end and gave a hit with a heavy hammer to get it moving, and had the quill resting on 2 blocks on the floor with a rag between them so it didn't have far to fall.. As long as you protect the end you will be fine.

For the pulley bearings I used a piece up steel tube in the vise and pressed it out that way. From memory I used another smaller piece for the center once it got moving down.

You will get a laugh out of my plastic spacers they put between the bearings, not sure if your will have the same.I replaced them with steel ones.
The whole lot comes out as one after removing the internal curclips.



Sounds like your getting the price of the bearings down, they should be cheaper over there than here as everything else is.

Looking forward to seeing your projects.

Dave

Hey guys,

as you know I just replaced my quill bearings with standard good quality Japanese ones. Should I perform a run in period of 20 mins at every speed, or not bother?

Hey Dave,

Also I had a play with my quill backlash. It appears that about 50% is in the quill rack and pinion and probably about 90% of the rest is actually backlash between the worm and worm gear in the quill fine feed. It's freakin backlash city!

Also, to fit eccentric bushes in the mill head, do you need another mill to bore the bush seat on the RHS? Or do you fit a bush into the existing hole and turn down the shaft? The LHS is easier as it already has a removable cast bush held in with 3 cap head screws..


Cheers,

Simon

Hi,
I would run your bearings in again because they need bedding in.
I thinks 10 minutes is enough and only did mine in low medium and high.

I removed the dowel pins in mine not long after I got it and brought the housing/worm down onto the gear more to take some out, try this on yours. I had to remove the socket head screws and replace them with normal bolts and washers, so the bolt heads wouldn't go into the counter sinks.

With the rack and gear, just check while it's out to see if when the 2 are brought together it will take out the back lash. What I found with mine was the gear teeth where slightly smaller than the rack which gave the back lash. So bringing them together would accomplish nothing but binding.

If yours will come together and remove the back lash, I have a simple idea of how to do with a hand drill and a line boring type of set up, but will have to draw a picture to explain it.

Also do you have any grub coming up from underneath into the holes on each side in the castings? I have one each side in mine, the right one stops the shaft moving sideways, while the other is for the quill spring adjustment onto the cast bush.

Dave

Thanks Dave,

At this stage I really have no idea where the quill rack sits in relation to the pinion. It may as you say be as close as it can be already. One day when I pull it out again I will try to do some measurements.

I ended up running the mill for about 20mins at every speed, mainly to check I had not overdone the preload on the bearings. The preload on these bearings seems pretty forgiving, I did my up to where I figured was OK, and then a bit more just so the castlelated lock washer tab would line up with one of the slots. I was worried I may have done it up too much but after running it, it only got warm to the touch.

Hey CJ,

I was reading another thread (show us your mill) when I realised that you live in US. I wondered how you got a Grizzly mill until I saw where you lived! Welcome!

Cheers,

Simon

I wonder if Eskimo can remember where this goes...



I think this is a new record... what is it two years?

Regards
Ray

Came up looking good Ray,
It was only December 2010 when you made it, so you where a bit quicker than 2 years, LOL
Just stick to the excuse you needed to test it over time to see if it was a good design. Now at least he has a proven product.

Eskimo,
We expect this to be fitted soon after all your complaining,

Dave

Originally Posted by RayG

I wonder if Eskimo can remember where this goes...



I think this is a new record... what is it two years?

Regards
Ray

Has it really been that long...gee you slack Ray

Also, your right....where does it go again......can you please send drawings and 3 copies of written description of how to fit it!!!

Originally Posted by Dave J

Came up looking good Ray,
It was only December 2010 when you made it, so you where a bit quicker than 2 years, LOL
Just stick to the excuse you needed to test it over time to see if it was a good design. Now at least he has a proven product.

Eskimo,
We expect this to be fitted soon after all your complaining,

Dave

and i thought you were on my side Dave.....

Originally Posted by RayG

But its not finished..it hasnt been blackened...okay, okay,.... I'll accept it as is hahaha

What do you think of the taper bearing now it's in Eskimo, Oh you haven't fitted it yet.

Dave

Yea the part looks great! I would like to know how its working for other people as well. I ordered all the SKF's last week and got them down to $141 before tax and shipping, although they are shipping from only a few hundred miles away so it shouldn't be to bad. Also ordered the materials and a single point threading bar so I think I'm all set. One question I have and I know this has been brought up before. How are you gauging the preload? Some people are using the break in test with temperature by feel as a measure. Are there any other ways, like spanner with torque? I wasn't able to find any torque specs on the spindle bearing preload anywhere. Hope to start on this when everything finally comes in. Probably won't receive the material for another 2 weeks if the shipping time is anything like the last time I ordered. I'll also be practicing some single point threading before I try it on the real deal .
-Chris

Originally Posted by cj2025

Yea the part looks great! I would like to know how its working for other people as well. I ordered all the SKF's last week and got them down to $141 before tax and shipping, although they are shipping from only a few hundred miles away so it shouldn't be to bad. Also ordered the materials and a single point threading bar so I think I'm all set. One question I have and I know this has been brought up before. How are you gauging the preload? Some people are using the break in test with temperature by feel as a measure. Are there any other ways, like spanner with torque? I wasn't able to find any torque specs on the spindle bearing preload anywhere. Hope to start on this when everything finally comes in. Probably won't receive the material for another 2 weeks if the shipping time is anything like the last time I ordered. I'll also be practicing some single point threading before I try it on the real deal .
-Chris

Hi Chris, I will be interested to see any fresh responses to this question too. I have seen many a discussion about this. Some say measure the temperature, if it's not too hot to touch it's fine, some say 25 or so Deg (Celsius) above ambient. I have heard that some people measure the end play to torque it up until all the endplay disappears.

With my lathe, I nipped it up for starters and then measured the movement of the spindle by levering the 3 jaw with a big piece of timber. Once I got it to a point I was happy with, I then ran it for 30 mins and monitored the temperature of both bearings with a non contact thermometer. They ran warm but not hot, at about 25 deg above ambient.

I'm probably clutching at straws with my approach as there is probably a much more precise method but it seems to work for my case.

Also I think with the lathe, it's easier to measure the temp of the bearings than the mill so there may be a more suitable method. The spindle bearings on my lathe are oil lubricated where as the mill they are grease so I'm also not sure if that means they run hotter or are preloaded differently. I did the preload on my mill last week, it seemed a bit hit and miss but there is little/no appreciable movement in the bearings and the lower bearing only runs warm after 1 hour, using all speeds.

Surely the ultimate in accuracy would be to measure the torque of the preload nut but I guess depending on the pitch of the thread, the torque requirements may be different in every case?

Interested to see what others have to say,

Cheers,

Simon