CNC lathe 5C spindle build

[aarongough]

Emco thinks it's good enough for a lathe There are many paths to success.

BTW.. Not much point in using precision duplex bearings at the front unless you also use a precision bearing on the rear.

Definitely, given that you were able to show me a concrete example of that type of seal in use...

Honestly I don't know what to think right now. The initial goal of the build was simple, cheap, and working. But it's gone a long way from that already...

Once I get this thing built, I'd love to be able to put up the design for other people to use. But for that to work the design needs to be as simple as possible and bulletproof.

I think that using the matched A/C bearings is a simplification that is worth the extra expense. The labyrinth seal stuff seems like it could get as complicated as you want it to be, so I'm not sure where the happy middle ground is there.

I think the seal design that I've come up with is largely analogous to what Mactec is using, but who knows if I'll actually be able to machine it! But if I go to all that trouble just to find out it's not needed that would be a pain.

The real problem is that anything I make, I'm not going to know if it works until I kill a set of bearings through contamination. That makes me want to go with the best design, but the fit needed on these seals is somewhat daunting for a guy like me that's still wet behind the ears...

Good point about the rear bearing. At least it's a common and relatively cheap type.

[aarongough]

I don't mean to sound ungrateful with all this by the way, I appreciate all the help!

Once I get this damn thing built I'll buy you all a beer or two!

[lakeside53]

LOL... no issues... The problem with design-by-committee is that you get way too many good ideas, and you have to choose which you'll use. If you don't use mine life will still go on, and I'll still take that beer


And.. that rear 6209 may be common, but it's not cheap in any real precision class. ABEC5 (P5) may be more reasonable though. And then... can you find one with seals/sheilds.

Here's a P4 (no seals..) - offer him much less! http://www.ebay.com/itm/TORRINGTON-F...item43b891f3e4

[mactec54]

lakeside53

What Emco is using is very crude at the least, I have 3 Emco CNC machines & they do not have anything like what you have, I guess they did not take to much care with the manual machines, You have to look at the whole picture of what you have though, this type is very common,( not quite what you have but similar ) for manual machines, they get away with it like this, because you have the large diameter of the camlock flange this is quite close to the face of the housing, so this in it's self keeps most of the chips away from the bearings

When you have a collet chuck only, like what aarongough is using, you don't have this protection, so you have to make a good designed labyrinth type seal

[mactec54]

aarongough
The labyrinth seal stuff seems like it could get as complicated as you want it to be, so I'm not sure where the happy middle ground is there.

If you are making, building, machining parts for the rest of the machine, this is no different & is a very basic part to machine, If you do a good drawing of the parts, which you can do, you then make the part to the drawing, if it's not right then you make it again

[aarongough]

aarongough
The labyrinth seal stuff seems like it could get as complicated as you want it to be, so I'm not sure where the happy middle ground is there.

If you are making, building, machining parts for the rest of the machine, this is no different & is a very basic part to machine, If you do a good drawing of the parts, which you can do, you then make the part to the drawing, if it's not right then you make it again

Thanks Mactec, I think I'm just getting antsy because I'm used to 'doing' rather than sitting down and re-designing for this long!

Did the labyrinth seal in the last drawing I posted seem reasonable? As far as I can tell it looks similar to the one in your print, just assembled differently.

-Aaron

[mactec54]

aarongough

Yes it looks ok, but will need a lot of care when you assemble it, this is a little easier to make, When you assemble it, if you could put a long tube/spacer on the spindle behind the bearings, & lock it up just tight,with the locking nut on the back, this will make it eaiser to assemble, then the only loose part will be the threaded nut part of the labyrinth seal

[lakeside53]

lakeside53

What Emco is using is very crude at the least, I have 3 Emco CNC machines & they do not have anything like what you have, I guess they did not take to much care with the manual machines, You have to look at the whole picture of what you have though, this type is very common,( not quite what you have but similar ) for manual machines, they get away with it like this, because you have the large diameter of the camlock flange this is quite close to the face of the housing, so this in it's self keeps most of the chips away from the bearings

When you have a collet chuck only, like what aarongough is using, you don't have this protection, so you have to make a good designed labyrinth type seal

There is another piece of "finishing" sheet metal that snugs up around the spindle. I guess that helps also.

[aarongough]

Alright guys!
Here's the final drawing (I think) before I get started building this thing!

The materials:
Bearing retainer nut - C1144 Stressproof
Inner and outer labyrinth seals - C1144 Stressproof
Bearing stack spacer - Seamless Tube 2.25 OD x 1.685 ID
Rear bearing shield - C1144 Stressproof
Jam nut - Either seamless tube or C1144 depending on thread depth
Headstock block - 6061-T6 Aluminum

Any pitfalls here guys? I haven't used C1144 before but I hear it's nice to work with.

I'm going to pick up the materials on Thursday. I'll also order all the bearings next week.

[ninefinger]

Any pitfalls here guys?

I see only one jam nut on the back. Typically there are 2 to prevent loosening.

Why is there a radial groove on the outside of the labyrinth seal? How do you plan on tightening it (the bearing retainer/labyrinth seal)? I think a couple of holes for a pin type spanner would be simple and effective here. The other alternative is to not thread the headstock and use a bolt-on labyrinth seal and bearing retainer, similar to what is seen in the drawings I posted earlier. It would seem easier to make to me....

Mike

[aarongough]

I see only one jam nut on the back. Typically there are 2 to prevent loosening.

Why is there a radial groove on the outside of the labyrinth seal? How do you plan on tightening it (the bearing retainer/labyrinth seal)? I think a couple of holes for a pin type spanner would be simple and effective here. The other alternative is to not thread the headstock and use a bolt-on labyrinth seal and bearing retainer, similar to what is seen in the drawings I posted earlier. It would seem easier to make to me....

Mike

Hey Mike!
The bearing retainer has 4 holes for a pin type spanner, 2 of them intersect the cut plane for the section view in the drawing, and I turned on the 'show only cut faces' option to make the drawing clearer which is why it looks like a groove. Great catch though and sorry for the confusing drawing!

I had 2 jam nuts on before and Mactec seemed to think that having 2 would be unnecessary if the thread pitch on the nuts was fine enough, like 32TPI. I'm fine with making it 2 nuts, though it will make things a bit tight for fitting a collet closer! I'm also fine with using one nut + loctite if the consensus is that's enough.

[ninefinger]

1 nut with thread locker will be fine.

Good luck and let us know how it works out.

Mike

[aarongough]

1 nut with thread locker will be fine.

Good luck and let us know how it works out.

Mike

Thank-you sir! Thanks for all your input by the way!

Hopefully I'll get started this weekend, I will be posting a build log as I go. I know a lot of people have talked about making a 5C spindle from a spin indexer, but I've never seen it done!

Hopefully it's something that works out, because if it does I think the zone may see a few more CNC lathes over the next little while!

I'll post updates as they come.

[aarongough]

Turns out my supplier doesn't have CD1144 in diameters greater than 3" (even though they list it on their line card...)

So I'm going with 1018 CRS for all of the labyrinth seal parts... They also didn't have the DOM tubing that I wanted, so I'll be making the bearing stack spacer from solid CRS round bar as well... I'll be making a lot of chips by the sound of it!

[lakeside53]

If you want to make things easier on yourself (especially wrt surface finish) make the seals from aluminum. If you want really tough stuff... 7075-T6xx - almost as strong as mild steel.

CDS also has a lot of internal stress that make to hard to hold a "flatness". I'd use HR if I was going that way. You can etch off the mill scale if that's objectionalble.

[Bob La Londe]

Turns out my supplier doesn't have CD1144 in diameters greater than 3" (even though they list it on their line card...)

So I'm going with 1018 CRS for all of the labyrinth seal parts... They also didn't have the DOM tubing that I wanted, so I'll be making the bearing stack spacer from solid CRS round bar as well... I'll be making a lot of chips by the sound of it!

If you are in the states there are a lot of vendors who will ship small pieces at reasonable prices. Speedy Metals, Stock Car Steel, Metals to Go, etc... If you can't find direct links you can always contact them through Ebay. They all sell there. I buy blank cut pieces of 6061 for one of my regular type jobs from Stock Car Steel all the time, and they ship to me in USPS flat rate boxes if they will fit (if I remind them first). Some of the other vendors will too.

[aarongough]

If you want to make things easier on yourself (especially wrt surface finish) make the seals from aluminum. If you want really tough stuff... 7075-T6xx - almost as strong as mild steel.

I was considering that as I generally work with aluminum anyway, and am used to dealing with it. I figured it would wear too quickly or something.

I'm going to go ahead with the CRS for now as it's good experience to work with materials that I'm not used to.

If I'm unable to get the parts made then I'll fall back to 6061-T6 in shame

[aarongough]

If you are in the states there are a lot of vendors who will ship small pieces at reasonable prices. Speedy Metals, Stock Car Steel, Metals to Go, etc... If you can't find direct links you can always contact them through Ebay. They all sell there. I buy blank cut pieces of 6061 for one of my regular type jobs from Stock Car Steel all the time, and they ship to me in USPS flat rate boxes if they will fit (if I remind them first). Some of the other vendors will too.

I'm based in Canada, and unfortunately we're a bit more limited in selection up here.

I'm using a company called McKinnon Metals, I've found them to be helpful and quick. Their prices seem ok for the most part too. Their selection is just not quite as large as I would like.

[lakeside53]

I was considering that as I generally work with aluminum anyway, and am used to dealing with it. I figured it would wear too quickly or something.

I'm going to go ahead with the CRS for now as it's good experience to work with materials that I'm not used to.

If I'm unable to get the parts made then I'll fall back to 6061-T6 in shame

wear? they are not supposed to be contacting


With CRS... most of the the stresses are in the surfaces, so machine both sides off equally if that's possible.

[aarongough]

wear? they are not supposed to be contacting


With CRS... most of the the stresses are in the surfaces, so machine both sides off equally if that's possible.

The way I machine them, they may well be contacting

I meant wear from swarf mainly... I imagine it wouldn't be too bad in any case.

I bought the CRS 1/4" oversize so that I can skim off the stressed 'skin' before doing any other operations. Hopefully that should make sure that nothing moves around too much.