Worn Headstock Bearings dunlap wood lathe

[Jim Constantino]

Hello Everyone

I accidentally posted this in another forum - sorry.

I am new to this site and new to wood turning. I was given an old Dunlap wood lathe, see attached pics. when I 1st received it I noticed the headstock bearings were worn - about an 1/16th-inch of play on spindle. The bearings or bushings were oilite bronze 3/4-inch ID and about a 1-inch OD. Local bearing shop provided replacement bearings/bushings which I installed. I have about three or four questions regarding this issue, so here goes;

1) This is where my problem starts - with new bearings in place the spindle would not fit, but dry fit before pressing into headstock the bearings were fine. I assumed the OD was somewhat oversize and compressed the bearing a little. I purchased a brake hone and honed the bearings until the spindle slipped in OK. The spindle spun freely and I ran the lathe with no load for about 15 to 20 minutes and checked the spindle still spun free which it did. I added felt to the oil cups and use non-detergent oil for lubrication. When I set up the lathe with a drive center and free center on the tail stock they were slightly out of line vertically - about a 1/16th-inch with the headstock center higher (I think, memory isn't great). Now after making about 15 small handles for Xmas presents :) the bearings are shaking about a 1/16th to 3/32nds of an inch.:(

2) I had to build a lathe stand and wanted to mount motor below lathe. As photo indicates it is on a hinged board. Since I was not sure of belt tension I added a 3/8-inch threaded rod to support the hinged board. I also used a link belt. I have searched internet about aligning a wood lathe and have come across some descriptions that include leveling the stand and the lathe base both across and along the length and shimming the headstock and/or tailstock so that the centers are in line. Any suggestions here????

3) While making the handles - mostly pizza cutter handles out of maple, I made a jig that mounts in a Penn State Economy chuck. The jig is a square block with a 5/16 lag screw by 5/16x10 metal screw in the center. I center my handle stock on drill press and drill 5/16th pilot hole, then drill another larger hole to accept the 1/2-inch insert. I install the insert then mount the handle stock onto the jig and bring the tailstock upto the center of the handle stock and tighten everything into place. It seems to work OK. I can pretty much finish each handle with the one set-up and the final cut off involves a small amount of extra sanding and the handles are complete.

4) I have no experience with lathes prior to this. No manual on setup. I have been making Xmas presents for family and friends for over twenty years so have some experience in the wood shop.

4) If I just replace my bearing again I assume I will have the same problem again. Issues are; is the belt tension a problem, is the center alignment a problem, is the jig a problem, or/and is this a lathe setup problem.

thanks in advance for any help
Jim
http://www.sawmillcreek.org/images/misc/paperclip.png Attached Thumbnailshttp://www.sawmillcreek.org/attachment.php?attachmentid=277432&stc=1&thumb=1&d=1387377889 (http://www.sawmillcreek.org/attachment.php?attachmentid=277432&d=1387377889)

[Dave Cullen]

I'll take a shot at some of your questions..


1) This is where my problem starts - with new bearings in place the spindle would not fit, but dry fit before pressing into headstock the bearings were fine.

Bronze bearings are often undersized and require reaming, but in my experience the fit shouldn't change after being installed. If the fit after installing means you couldn't fit the spindle through either bearing then I'd say you're right and they get compressed a bit. If the spindle fits through individual bearings but not through both then it's an alignment problem front to back. I dunno how you'd fix that.

Bearings wearing that quickly means they're under a lot of stress or without lubrication. Oilite is really good about soaking up oil though, and should last a long time between oilings.

I've used the same method of hanging a motor on hinges and letting its weight keep tension on the belt. I doubt that's your problem.

What's the condition of the spindle itself? Does it have any pits that could abrade the bushings? Did you find bronze dust from rapid bushing wear?

[roger oldre]

As far as the alignment of the centers for spindles it wont make a differance. If they are out of line it will not be a good idea to chuck up in a chuck or onto a faceplate and then use the tail stock for stability. This will induce an abnormal load on both the spindle and the tail stock.

[Jim Constantino]

Dave Roger thanks for the replys. The bronze bearings were installed individually. I do not have a press and did not remove the headstok from the bed. I used threaded rods and deepwell sockets to pull the bearings into the headstock. I even froze the bearings and used a heat gun on the headstock. The bearing would slide right on the spindle before any attempt to install. Once a bearing was installed the spindle would not fit. I used a brake hone for about 1/2 an hour on each so the spindle would fit. The oil wells seem to be providing lubrication and I see dark oil where the spindle and bearing meet. The spindle seems to bee in very good condition and had no signs of wear - maybe a few .001-inch on the inboard side of headstock.

Any suggestions on how to align the head and tail stocks?

I suspected using the chuck and jig I made with the misaligned tailstock might be applying too much stress. I am not confident using two centers to make these handles. Directions suggest installing the threaded insert before turning - this allows a better grip on the unturned wood while installing the insert. I guess I could remove the chuck, install a drive center, place the end with the insert at the tailstock, and try turning handle. Any suggestions???

[Dave Cullen]

If one end of the turning is hard mounted to the headstock and your centers are out of whack, that might explain the rapid wear on the headstock bushings but I think you'd have other issues that would give you a clue. At any rate, a 1/16th of an inch of headstock play is unacceptable so it seems you need to revisit the bearings again. I have used a brake hone to ream bronze bushings in the past and unless you got carried away I don't see that as your main problem.

Lathe centering is not always simple to accomplish. If the bearings are not adjustable the only option is shims under the headstock. That can work for vertical alignment but not side to side. If you have a #2 Morse Taper at headstock and tailstock, this nifty tool can show you what the alignment is:

http://www.woodcraft.com/Product/2007361/43362/NOVA-2MTNA-Acruline-2MT-Alignment-Lathe-Accessory.aspx?keyword=&refcode=10INGOPB&device={device}&network={network}&matchtype={matchtype}&gclid=CL-UocTdvLsCFRWUfgodhT8Ahg

Once you've installed the insert you can screw a homemade wooden adapter into it that lets you drive the work with a spur center. They are very forgiving of lathe center alignment.

[roger oldre]

is the play radial or axial? It is fairly easy to determine what is out of whack on the lathe. The above tool will check for alignment only at one given spot on the lathe. even with this tool the lathe can still be off. Start with the headstock. get a cheap dial indicator to check the play in your plain bearings first. then check the runout through a rotation. Install your chuck carefully checking for material in the threads or where the chuck bottoms out against the shoulder. put a piece of shafting in the chuck and check the runout on both ends of the shaft. also check the movement of the shaft when checking the bearing movement radially. Now the trick is to at least get your headstock in line with the bed of the lathe to start with. You dont have a cross feed so you will have to get inventive. measuring the difference both horizontally and vertically to the shaft at its extremes. once this is done you can determine what is needed for the tail stock in a similar means. Turning between centers for long items is the best answer.

you can try this for a quick no set up no tool check:chuck a piece in the chuck and bring the tailstock up close but not touching rotate the headstock and watch the path of the tailstock center. if you want you can bump the tailstock center on the stock and then back it off again till it is out of contact and then rotate and watch. Or bump the tailstock rotate the piece 180 degrees and bump again. this will tell you how far off you are. at that point try a short piece first then a long piece. if it stays the same the tailstock is your culprit if it changes the headstock is to blame.

use slick 50 or a tacky oil additive forget the felts they are there to slowly drip the oil into the bearing area. Did you drill oil holes in the new bearings?

[Jim Constantino]

Dave Roger thanks you guys are good!!! I was at the lathe today and removed the chuck, installed the drive center, and made three more handles then the spindle siezed and it was too hot to touch.
I took the spindle out. The inboard bearing was dry and worn on the bottom causing the 1/16+ of play. The outboard bearing was well lubed and still snug.
So I used an old bearing because I knew it would fit and used the spindle to drive the worn bearing on the inboard side out and the old bearing into place. Play is gone, but it was still vertically off by about a 1/16th. So I took the tailstock apart and added .0016 of shim stock to front and back of tailstock. Seems to have worked. I made one more handle with no problems so far and no heat.
Thanks Jim

[Richard Coers]

Decided to post over here instead of the woodworking post.
Oilite bearings are porous. Cleaning with WD40 would not get the grit out of the pores. In fact, WD40 probably leached out the lubricant that was in the bearings. I still think the hone and now WD40 killed them. If you had a hard press on the bearings to install them, they will be undersize. No way to machine them at home to proper size and alignment. That's a job for the machine shop with a reamer and stiff metal working machines.
Directly from the oilite web page; http://www.oilite.com/bmp.asp
Honing and grinding are never recommended on Oilite® bearing materials. Using these methods on any surface which will become the bearing surface will introduce grinding media and could easily smear the bronze pores sealing the micro-porosity.
And then about oil;
After extensive machining, bearings should be re-impregnated with appropriate / specified oils. Vacuumed impregnation is recommended. If bearings were not lubricated prior to machining and if cutting fluids were used, that medium must be removed prior to any impregnation of the oil selected for the application. Your authorized distributor can provide oils for re-impregnation after machining.

[Jim Constantino]

Richard thanks. I checked out the Oilite website and see what you mean. Not very encouraging if you do not know a machinist. I reinstalled the tightest old bearing and am hoping I can finish 8 more handles before Xmas without another bearing failure. Do you know another solution for bearing replacement on old dunlap/atlas/craftsman lathes???