Building a New Lathe

[vintageandclassicrepairs]

Hi Steve,
I glad to see you are back at the lathe build 
You could have made the excuse that the castings were "curing"  LOL
Honestly, I missed your contributions to the forum

Keep up the good work
John

[vtsteam]

Thank you, John.  I've slowed a little -- yesterday's project time allotment was spent thinking about the headstock cap -- which I'm going to have to make a pattern for and cast. Fitting it to the bearings, and also bolting it down is a little tight for clearances due the lower casting dimensions --- already fixed. This will be the first thing I've ever made with tapered roller bearings. They take up a lot of room.

I'm hoping I can squeeze in 5/16" cap bolts instead of 1/4"..... they both seem a little small, by eye.

[vtsteam]

I know to set the axial pre-load when installing the spindle, but I'm wondering how much installed radial load, (if any) is usual for tapered roller bearings?

The question comes about because I am going to have a split housing. I don't want to compress the bearing more than necessary with the cap. The bearing space will be bored with the cap in place, and a few shims between, for adjustment, although hopefully unnecessary..

Is a slightly tight fit all that is necessary, or is there usually a required minimum interference fit spec for pressing them into a normal (un-split) bearing housing?

I know from replacing bearings in existing equipment (and replacing wheel bearings), you need a puller, but re-installing there seems to be just a light interference fit. If it isn't critical, that should be pretty straightforward to achieve.

[krv3000]

in a word brill

[PekkaNF]

You want rings fixed on seat and on shaft. If the outer ring moves, it will rotate slowly and soon it will be loose. Therefore sometimes the ring is glued if it can't be pressed. There are some variations, but this is the main rule.

Still wondering this headstock booring. I have a Gingery's book and I am familiar with the principle. Was wondering if you considered using the tailstock to bore bearing for fixed steady, that could be put permanently behind of the head stock for support when ou are boring the head stock?

This is most interesting project in long time.

Pekka

[vtsteam]

Thanks Bob!
I miss seeing you restore an indicator every once in awhile! I have one that I am working up the courage to work on a .0001" version with a very yellowed lens and zero off to one side. Cheers! 

Pekka, that makes sense, and since I have a cap with shims, adjusting a for little pressure on the outer bearing ring to keep i from spinning will be easy.

I see, re the boring bar -- make a boring bar with the cutter in the center instead of a cantilevered bar and support the far end in a temporary steady behind the headstock. Good idea -- I like it! The boring will go faster because chatter will be reduced to allow a deeper cut. 

 

[vtsteam]

No work on the lathe today, I'm building my daughter a playhouse for her birthday. Dropped a hemlock tree, and hauled a section to the sawmill, then cut siding for the structure, and nailed it up by dinner time. Too tired to go out to the workshop.

[Neubert1975]

I hope you will Neubert, and show us pics, while you do!

I've had the same experience in the past of buying a machine and then realizing the disappointment of no longer needing to make one.

I know I will finish this lathe, when I can, and I originally intended to make it a halfway decent mill of it, too. I planned to sell some of those other machines when this one proved out.

There's a big difference for me in satisfaction in using a tool I built, and having it just what I need, the way I imagined it. The Gingery lathe and attachments were like that. This one was designed to be a much more rigid machine, but not much larger in footprint.

I do own a 12" x 36" Craftsman lathe, but I don't need the 36" length. This machine has the same ways dimensions and rigidity as that one, but will be sized closer to the Gingery in footprint. So I hope it will be capable of some reasonable milling, and solid turning without as much concern over chatter.

If i build one i promice to take lots of pictures, but time will tell if i build one.
I do have one picture of the mill i build, only with a tiny proxxon cross slide table on it, and a 24 volt motor for testing purpose.
at the moment i am talking with a guy on a danish machinist forum, that when he is done using it, has offered mea scaltools bk45 mill drill at a verry fair price.
its a gearhead, barley used mine for 6000Dkr, cost from new in Denmark 30.000Dkr

But for sure it is a big satisfaction to use a tool that one has made by him self 

My lathe is okay, but far from a good one, its a weiss wm250v

[RussellT]

Hi Steve

It's good to see you back on this project and forum.

I would have thought the main consideration with your proposed bearing design was that the outer race shouldn't be squashed out of round - which it might be if you removed shims from a round bore.  I think Pekka's suggestion of taking up clearance with some glue might be better than shims.

Russell

[vtsteam]

Neubert, great to see your homemade mill! I do love that kind of thing. It's the true MadModder style! How about a thread about it, if you have construction photos (or is there one already that I missed?)

Thanks Russell, good to be doing something here again!

I'm not worried about squashing bearings for several reasons. First is that I hope to bore to a good interference fit in the first place! Second is that, I would never compress a cap to the point of "squashing" a bearing. It's fairly easy to tell if it's deforming if you feel for any resistance as you twist the spindle back and forth while tightening the cap bolts.

All split bearings ever built, including very thin automotive plain bearing shells, have the same potential theoretical problem, but work in practice, IF the fit is reasonably close to start with. The bearing housing limits side expansion of the shell, which would create ovaling.

In the present case, besides a good fit, the adjustment range is .0005" per shim, since you can remove a .001 shim per side. Anyway let's not buy trouble, and hope for the best. Absolute worst case scenario of a terrible bore pass, I'll cast new parts, and learn a lesson!   

[awemawson]

Steve,

You look to have ample meat around the spindle, that if things went pear shaped you could bore out over  size and fit a bush

Looking excellent so far 

[vtsteam]

Maybe, Andrew. I suppose you could shim the circumference too, if oversized. Many possibilities. We'll see how ham-handed I am with the boring.....

Pekka, I'm still thinking about the steady rest behind the headstock idea .....I just realized something. I think I already have one to fit this lathe, since I made the ways the same dimensions as my Craftsman lathe! How simple!   

I have to go check.........

[vtsteam]

Well, no, after measuring it was originally for an 11" lathe, I had made a riser block to suit it to the 12" Craftsman, but removing the block didn't bring it down to suit the 9" new lathe. I could mill the base down, but don't want to.

However, I also had once made a steady rest for the Gingery lathe, mine is a 7-1/2" dia. So bolting a 3/4" riser block to that steady is just a matter of casting one, and I can suit it to the new ways width. Easy mod. And I actually like the Gingery steady better than the bigger cast iron version. So, yesss! 

The Gingery steady sitting on the new lathe:

[PekkaNF]

That looks like a plan!

Pekka

[Neubert1975]

Neubert, great to see your homemade mill! I do love that kind of thing. It's the true MadModder style! How about a thread about it, if you have construction photos (or is there one already that I missed?)

I would love to make a thread about it, but i do only have that one picture, and the mill is long gone, in exchange for first an x2 mill and since the lux drimill ry-20 that i have now.

[vtsteam]

This winter and spring really took a toll on the little shop -- lots of rain alternating with deep cold froze ice onto the floor. It's all now just thawed, but still very damp in there. Lots of surface tool rust to deal with, and my furnace lining got wet and crumbly and will need to be renewed. BUT, I'm going to work on the lathe again -- just read through this whole thread to get my bearings again, so to speak. I think the next step I had planned was casting the headstock cap. I'll need to repair the furnace for that.....

[Neubert1975]

Good to see you back on the lathe build 

In December the guy who had offered me the scantool mill drill contacted me to let me no that i could now get it, and even at a lower price than first (now around 800 usd)
it is now sitting in my workshop and waiting for me to get ready to make some metal chips again 

Hopefully it will happen soon, though helf is setting the pace for me unfortunately.

[vtsteam]

Finally something new accomplished. After rehabilitating my Tiny Furnace, I had time today to make a pattern for the headstock cap.

[vtsteam]

Not a promising day or time to begin casting -- it's rained all day, and I finally cleared a little space under the open shed roof and located most of my stuff, weighed out some zinc and some 6061 aluminum to alloy with it (Zamak-12 -- 11% 6061). I had to run out and get propane as I was out of charcoal. No bench to work on, just the concrete floor. But cast I must! It was 4:30.

Stooped over flippin flasks isn't ideal. But anyway...... Also I realized I hadn't put core prints on the pattern, and I didn't want to machine away the lathe spindle passage. So I thought I'd be clever and try a simple half core, baked and laid on the drag. I decided to experiment and just ram and bake some greensand as the core, rather than the old tried and Gingery molasses and walpaper paste mix. Lots of new variables!

Anyway, here's the start:

[vtsteam]

Here's the baked greensand half core on the drag. Actually I was quite pleased with the way that baked out. Decent amount of strength and easy to place. BUT, it was a little too long, as you can see here and I had to cut out the cope a little to accommodate. Unfortunately by doing without core prints, I couldn't invert the flask and make this the cope, because the piece is loose. That reduced the head pressure I could achieve above the casting.

[vtsteam]

Here is the cope ready to replace. A little ragged around the sprue, because I'm working stooped over, and my back is under the shed roof dripline...but, hey I'm casting! You can see where I've relieved the end of the pattern hollow to accept the slightly too long core. 

[vtsteam]

And the pour. I had forgotten how extreme shrinkage is with Zamak. The sprue and riser were both topped up completely before it began to cool.

[vtsteam]

Now that's shrinkage!

[vtsteam]

Always hopeful at this point -- first sight of metal in the sand:

[vtsteam]

But no cigar. Nice casting otherwise, but a giant shrink cavity in the center!    I should have added core prints and done a proper baked core. Then the flask could have been flipped again putting the casting in the drag instead of the cope, and plenty of head pressure and molten metal to feed it.

Oh well, first time back casting after a couple year lapse, and my planned molding bench would have eased the back ache. But hey I POURED METAL today, and better things to come...