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

Hi Simon,
A 7206 is a 30206 and the same with the other one. The 7206 is the old Chinese number.

Chinese New Part Number:32010,Chinese Old Part Number:2007110E,FAG:32010X,KOYO:32010JR,NACHI:E32010J,NSKR 32010 XJ,NTN:ET-32010X,SKF:32010 X,SNR:32010VC12,STEYR:32010X,TIMKEN:32010X,ZKL:32010X,

That is the site I was talking about earlier, and you just put your bearing number in at the top and click on "click here to obtain details" and it will show you the equivalent new/old Chinese bearings and on most the equivalent brands with there numbers.

Dave

Originally Posted by Dave J

Hi Simon,
A 7206 is a 30206 and the same with the other one.

A 7206 is an angular contact ball bearing....

Originally Posted by cj2025

Thanks for the warm welcome Dave. I'm tied up Saturday but will have time Sunday to post pics of my mill and lathe. I'll focus on the mill first as my lathe and 4 Jaw seem to be capable of holding acceptable tolerances. I'll probably just break down the head assembly. Maybe the most challenging part will be threading the M40 1.5 nut that you made. I'll also have to ask my buddy to weld in a piece of round stock as I have no TIG or MIG. I will definitely have questions about that operation, i.e. did you use an full profile insert or single point, # of passes, helical angle, etc? But that's all getting ahead of myself. I'll start slow and work up from there posting and pics that might be helpful. Anyways thanks again and I'm excited to jump into the world of metalworking!

No problem, just take your time, your on a steep learning curve. LOL
You will find a great bunch of guys here willing to help you out with any questions and problems.

With the thread it's really not hard, but I recommend trying it on scrap (old pipe) or cutting a thread in the nut under size before you bore it out to the right size. It is only a fine thread so you don't even need to set your compound at an angle if you don't want to (I didn't)
The tool needed is just a piece of HSS ground with a 60 degree V and no other grinding like rake etc, so easy to make.

I will get up photos of the down feed insides as I have pictures of both the grizzly one and mine. You might be able to press fit the piece in first and then machine it in place on th worm instead of welding. A bit of locktite or grub screw could also help hold it in.

Dave

Originally Posted by .RC.

A 7206 is an angular contact ball bearing....

Your right, I think I typed in 7206 instead of 30206.
7206 is the old Chinese part number for the 30206 as can be seen in the link below.
http://bearings.ttzcw.com/enmcollate...acd7d788b.html

If anyone can make it all confusing it's the Chinese, LOL

Dave

PS
I will fix the link above for future reference and to save confusion

Hi Dave, Joe, Mike and Rc,

Thanks for the information. It makes a little more sense. I have spent some time studying the quill and have made some more observations. The outer race of the lower tapered bearing (30208) can be punched out as there are two small holes on the top side of the bottom quill. The holes allow access using a small punch to drift out the race so not as difficult as first suggested. It's amazing what you can learn just by taking your time to study parts!

Attached is a pic of the quill. You can clearly see the two holes at opposite sides of the quill base.

Second pic looking into the quill base and the bottom outer race. Overall the 45 size mill is a fairly straight forward machine to work on.

Cheers,

Simon

At least they thought to give you some hole for getting them out.

While I was in there I painted the inside of the quill so no rubbish would fall down into the bearings. I ran a wire wheel on a hand drill up and down the bore to clean it up first. A standard wire wheel wont reach so I used a spade bit extension between the wire wheel and drill to reach. If you don't have one you could easily make something on the lathe out of a piece of scrap 1/2 inch rod.

Dave

Originally Posted by Dave J

At least they thought to give you some hole for getting them out.

While I was in there I painted the inside of the quill so no rubbish would fall down into the bearings. I ran a wire wheel on a hand drill up and down the bore to clean it up first. A standard wire wheel wont reach so I used a spade bit extension between the wire wheel and drill to reach. If you don't have one you could easily make something on the lathe out of a piece of scrap 1/2 inch rod.

Dave

I wouldn't expect anything less of you Dave!

Hey while on the discussion of bearings. If anyone has been looking for a specific type of bearing or specific tolerance that they can't find here, give this crowd a go. Motion Industries - Keeping Industry in Motion they are in the US and they stock a huge range and their search function makes it easy to see what they have and if it's in stock. They also give a very competitive rates on shipping to Aus. I have bought a couple of bearings from them.

They also sell a generic brand called "Consolidated Bearing" these seem to be the cheapest of the good quality bearings. They are just repackaged FAG, SKF, NTN etc and sell them as Consolidated Bearings.

I bought a 30212 P5 from them for my lathe and it cost me about $200 delivered. When I opened the package, it was an FAG bearing made in Austria. The same bearing, same brand, same tolerance here would have cost me $450.

In hindsight I probably didn't need to buy such an extravagant bearing but at the time I just replaced the type and tolerance that was in there. Just not a Chinese one.....

Oh well there're in their now. I make sure I look after the headstock oil really well so they should never need replacing....

Thanks for the link on the bearings and the feed back as a customer, will store it away for future use.

With my quill I was going to bore it out to clean it up before painting, LOL but thought that was going overboard and would take away precise material/strength anyway,

Dave

Hi Dave,

OK you got me thinking so I took the quill COMPLETELY apart, as in I drafted out the bearing races as well (using the barely useable proprietary provided drift holes) and have a look at what I found. Nothing really surprising for a Chinese machine but a lot of casting crud under the bearing seat. Why do all Chinese bearing seats look like they have been machined with a piece of fencing wire?

Anyway, running my finger down the inside bore of the quill felt very rough (as you would expect) but upon removing my finger I found a combination of casting crud and flakes/particles of CI.

Now I know why you hit yours with a wire brush and painted. Think I will do the same whiles it's out. Why not, doesn't cost anything and at least you know it's nice in there with nothing dislodging onto the bearings.

Pic attached of the quill end and bearing seat. Just for your amusement...

While your your have it apart it's a good idea to paint it.
I tried looking for a picture of mine without the bearing to show how mine was machined where the side of the bearing seats, but I cant find one. On mine they did a good job or I would have just faced it off.

What you getting out of the quill is casting sand which is black. Mine had a thin coat of yellow on it but was coming off in spots, and was only painted to the casting sand.

Dave

Originally Posted by Dave J

While your your have it apart it's a good idea to paint it.
I tried looking for a picture of mine without the bearing to show how mine was machined where the side of the bearing seats, but I cant find one. On mine they did a good job or I would have just faced it off.

What you getting out of the quill is casting sand which is black. Mine had a thin coat of yellow on it but was coming off in spots, and was only painted to the casting sand.

Dave

I had thought of re-facing the bearing seat but I would have to be pretty darn certain that it was hold properly in the lathe. Would you use a combination of 4 jaw and the fixed steady and a DTI to assure it was spot on DC before machining?

As for the casting sand, I am too too used to removing that stuff from my machines! While not as good as a wire brush, even degreaser and a pressure washer gets a lot of it off.

I used the air needle scaler on the knee and other castings.

It's up to you if you feel confident machining it, but what you said is the way I would go about it. Your only machining the bottom so the set up is not that critical, but you would need to be pretty close.

Dave

Thanks dave.

In terms of setting up to machine the bottom bearing seat, the main constraint would be to ensure the quill runs concentric and that the machined seat is as close as perpendicular to the outer quill machined part that slides in and out of the mill head. Yes?

Thats right, if you look at it now it's already pretty bad in that respect. You only need to get it square to the quill, and the bearing have a slight radius on them so they don't go right into the corner.

Don't forget to put some sort of protection between the 4 jaws and the quill when you put it in.
I would get the steady mounted on the lathe to the left of the carriage with it open and plenty of clearance for the fingers.
Then mount the quill in the 4 jaw and true it up both ends (chuck end first).
Once you do that bring the fingers in gently against the quill. Don't forget to oil it up before starting the lathe. It should only need low speed so it shouldn't mark the quill, but if your worried about it, wrap a piece of emery (worn out is fine) around the job first with the emery side outward. The 2 ends of the emery get clamped between the join in the steady.This will give the finger contact a wider bearing area and less likely to mark it up.

Dave