Hf 7x10 Spindle, Bearing, & Transmission Gear Replacement

[Cavediver]

I recently purchased a used 7x10. The previous owner faced off the chuck registration boss, so I have to replace the spindle. While I have it torn down, it has been suggested that I also replace the bearings and swap the plastic transmission gears with a set of metal gears.

I have done a good bit of research and have read the disassembly guide, but I still have some questions.

Is a hydraulic press absolutely necessary? I don't have one and really don't want to buy one. If I am going to need one, I will have to find a local shop to do that work.

Spanners for the spindle nut: I don't have 'em. Will I be able to remove these nuts without them, or do I need to track some down / buy a pair?

Metal transmission gears: are there any downsides to installing them? I understand that a spindle lockup / crash with the carriage can break the plastic gears. Since the metal gears probably won't break and that stress has to go somewhere, what will break?

Tapered roller bearings: is the seating / run-in / preloading process difficult? I've neve done it before and have no idea how difficult it is to do right. Also, the spacer needs to be cut down; how precise does this need to be? I can't very well tun it down on the lathe, so I will have to do it by hand.

Thank everyone, and sorry for the long post. I'm reasonably mechanically inclined, but have no real idea how difficult this will be. At least the guide makes it look easy...

 

[TakeDeadAim]

Ill address your questions in order
Yes you will need access to a hydraulic press to get the bearings seated squarely. Having the spanners makes getting the nuts off the spindle and making the adjustments easier without causing damage to the nuts. I have gotten these nuts loose in a pinch using a punch and hammer but have always caused damage to the nut in the process. I don't like impact against precision roller bearings and the wrenches prevent that. You have a handle on the plastic to metal gears. If your going to use the lathe a lot and for a long time the metal gears will be worth the effort especially since you will have the machine apart. Setting and placing spindle or any high precision bearings requires following procedure and careful adjustment. Without that the expense on the precision bearings is wasted. The spacer needs to be square and precise. If pressure is not constant on the bearings adjustment will be difficult. I would consider having this cut by a shop so it works well for you.

I don't mean to rain on your picnic but this job, if you want to do it, must be done the right way if you want good results.

 

[Cavediver]

I don't mean to rain on your picnic but this job, if you want to do it, must be done the right way if you want good results.

Not at all, and thanks for the response. I will start looking for a shop to handle the press work tomorrow, and will also see about getting my hands on the spanner wrenches.

As for the bearings, perhaps I will skip the taper bearings and get the angular contact bearings instead, assuming those are any easier to set.

 

[brav65]

I was able to do this job without a press using various pieces of pipe, washers, and 1/2" all thread. If you have not ordered the spindle yet, get one from here

http://www.amadeal.co.uk/acatalog/4__Spindle_Upgrade_Real_Bull_Mini-lathe__CJ18_series_.html

You can then mount a 4" chuck or a. 3" chuck without an adapter plate. The total price was 50 Euros shipped to me. That works out to only a few bucks more than LMS for the standard spindle.

I also installed the metal gears and tapered bearing and love it. Slightly more noise than stock, but no big deal.

 

[Cavediver]

I was able to do this job without a press using various pieces of pipe, washers, and 1/2" all thread. If you have not ordered the spindle yet, get one from here

http://www.amadeal.co.uk/acatalog/4__Spindle_Upgrade_Real_Bull_Mini-lathe__CJ18_series_.html

You can then mount a 4" chuck or a. 3" chuck without an adapter plate. The total price was 50 Euros shipped to me. That works out to only a few bucks more than LMS for the standard spindle.

I also installed the metal gears and tapered bearing and love it. Slightly more noise than stock, but no big deal.

Nice find!. It looks like the registration area is larger in diameter than the one on the 80mm spindle. Doesn't that mean you can't use the original 3" chucks (55mm recess on the back)?

 

[brav65]

Good catch , I have not tried to see if the 3" will fit. I guess if I needed to I could make an adapter plate.

 

[royesses]

On removing the old spindle, it is not as complex as it seems. When you get the bearing shields screws (the plastic covers over the bearings)removed and the rear spindle spanner nuts and gear and spacer off, you can use a block of wood and a ball pein hammer to knock the spindle and front bearing out. Mine came out easily. Then use a long taper punch or drift to knock out the rear bearing. You can remove the snap rings from the intermediate shaft and tap the shaft out and remove those gears if needed. You will need to remove the front bearing to get the front bearing shield cover off the spindle. A bearing separator works for this, but you could place two pieces of flat bar across an open vise jaws to support the bearing while you tap out the shaft.
The new tapered bearings must slide on the spindle shaft in order to be pre-loaded. You could do this in a drill press by holding 400 grit wet/dry paper to the bearing seat areas on the spindle. Stop and check the fit frequently. They must be a palm fit to the new spindle. Just loose enough to move but not pressed tight.
The outer races will need to be pressed into the spindle housing. You could do this with wheel bearing race driver kit like Harbor Freight sells. In the old days we used to knock in wheel bearing outer races with a ball pein and a 3/8 drive 6" extension bar. That's how it was taught in automotive school believe it or not. The extension bar is soft enough not to chip. You could also turn some plates the size of the races minus about .030 and drill 1/2" holes in the center. Then use a piece of 1/2" x 13 tpi all- thread and nuts and washers to pull in the races. Or a local auto parts store may be able to press in the outer races for you. The tapered bearings require some pre-load. Use a dial indicator to measure spindle end play then slowly turn in the first spanner nut until you just get "0" end play. Then tighten just tighten a tiny bit more . Too much pre-load will cause excessive heating of the bearings and early failure. I'm sure some of the experienced machinists here will have a better way. When running in the new bearings check for heat at the spindle and around the bearings. If they are warm it is okay. Hot is bad.

The spanner wrenches are the best tool for the job. Using a punch besides marking the spanners up, there is no way to prevent the front spanner from from tightening as the rear spanner is turned to lock them. You can purchase adjustable spanner wrenches from Enco and most other machine/tool supply stores. They are expensive though.

Hope this helps you a little. Just take it one step at a time and think out all your steps. Questions while you are doing it, just post your question on the forum. The factory uses rawhide hammers for all this as per the link below.
http://www.mini-lathe.com/Mini_lathe/Tuning/headstock/headstock.htm

 

[Cavediver]

The outer races will need to be pressed into the spindle housing. You could do this with wheel bearing race driver kit like Harbor Freight sells. In the old days we used to knock in wheel bearing outer races with a ball pein and a 3/8 drive 6" extension bar. That's how it was taught in automotive school believe it or not. The extension bar is soft enough not to chip. You could also turn some plates the size of the races minus about .030 and drill 1/2" holes in the center. Then use a piece of 1/2" x 13 tpi all- thread and nuts and washers to pull in the races.

I think I understand all of this. My ability to do it, well... I guess we'll see...
Re: pulling in the races: Will something soft like plywood or hardwood be OK for this? If not, will something a little more firm like 3/4" acrylic work?
I have access to a CNC router at work, and my choice of scrap in plywood, some hardwood, and a lot of plastics. I can easily route a plate for the job as long as I understand the objective and required materials. I'm guessing the wood or plastic will work fine, but thought I'd ask just in case.

I managed to remove the spindle nuts last night with a spanner from my dive regulator tool kit. It's not really the right size, but it did the job without messing anything up. I will likely have to come up with a different solution when I put them back on, but one problem at a time...

I need a new dial indicator as well. Will .001 resolution work well enough for this, or do I need to get my hands on a test indicator instead?

ETA: I now see that cutting a disk on the CNC won't work due to the angles involved. I'll see about checking a set of these out from one of the local auto parts stores (they provide free rental of some tools).

 

[royesses]

I think I understand all of this. My ability to do it, well... I guess we'll see...
Re: pulling in the races: Will something soft like plywood or hardwood be OK for this? If not, will something a little more firm like 3/4" acrylic work?
I have access to a CNC router at work, and my choice of scrap in plywood, some hardwood, and a lot of plastics. I can easily route a plate for the job as long as I understand the objective and required materials. I'm guessing the wood or plastic will work fine, but thought I'd ask just in case.

I managed to remove the spindle nuts last night with a spanner from my dive regulator tool kit. It's not really the right size, but it did the job without messing anything up. I will likely have to come up with a different solution when I put them back on, but one problem at a time...

I need a new dial indicator as well. Will .001 resolution work well enough for this, or do I need to get my hands on a test indicator instead?

ETA: I now see that cutting a disk on the CNC won't work due to the angles involved. I'll see about checking a set of these out from one of the local auto parts stores (they provide free rental of some tools).

It's doubtful that wood will be able to handle the stress of pulling in the races. On eBay they sell plasma or torch cut steel discs 1/4" thick and thicker. If you can get two of these just under the bearing race diameter size and drill the holes in them it would be optimum. Renting the driver kit from local auto parts might be a good alternative. Also packing the races in dry ice for a half hour or so would shrink them and make them go in easier. Just got to be quick doing it before they warm up. Our local Walmart sells dry ice. I've been known to put small housings in a 275 degree oven and dry ice the bearings. Then they just fall into place. Wife's don't like this! When I worked for CAT we used to put large ball bearings and races in a 20 quart deep fryer at 250 degrees to expand them and then they'd just slide onto the shaft by their own weight. I've replaced many diesel flywheel ring gears by heating with a torch to let the old one fall off and heating the new one using a torch and temple stick. They just slide on and when they cool they are locked solid.

The .001 dial indicator would be fine for checking end play. Sometimes you have to get creative when luxury money isn't an option. I didn't have a press when I replaced my spindle bearings with angular contact types. They had to be pressed on the spindle and pulled into the housing. I got creative with some pipe and all thread. I'm still not sure if I will eventually go with tapered bearings. Right now the angular contact bearings are doing the job well.

If you were closer to me I would help you out. I now have a 12 ton press. If you have any friends that can help you that would be great.

Roy

 

[Cavediver]

Thanks Roy, great info! Disassembly begins tonight, I should see what I am in store for by Wednesday or so. The parts are on order as well, so hopefully I will be rebuilding by this weekend.