Real Bull Machine 7x14 mini lathe headstock tapered bearing upgrade help please

[SLM]

 Hello forum!

I have a Real Bull Machine 7x14 lathe that I blew the headstock gears on so while I'm replacing those with metal ones I want to do the tapered roller bearing upgrade on. I've read (I think) every thread and guide on the internet. I'm more confused than I was! Some say the inner spacers in the headstock have to be shortened and / or have a shoulder turned for race clearance, another says you have to make 1.25mm thick spacers to ADD inside and others yet just mention having to shorten the back spacer.

Does it just depend on which brand lathe, what brand of bearing, how lucky you get? I'd really like to do this but as my lathe is broke I can't machine new spacers, etc. I'm sure I can shorten them on sandpaper.

Any and all help will be greatly appreciated! 

 

[Chuck in E. TN]

If we knew your location maybe someone close would volunteer to turn the spacer for you. As to the need or size, I cann't help there. I've not yet touched the bearings of my 7 x 14 MicroMark SEIG. Not sure at all about RB.
 
Chuck

[SLM]

Hi Chuck.  I'm in Ohio in the US.

Yes, if the extra internal spacers are needed, I'm going to need to buy them from someone. I just don't know what is or isn't actually needed at this point. Even LittleMachineShop.com just says the back spacer needs shortened by about .100"

[Chuck in E. TN]

If you find out exactly what you need, and can provide dimensions or better yet, a drawing, I'll make you one out of aluminum, or Delrin. You pay the post.That is if no one close to you steps up.
Any Real Bull owners out there that can tell SLM what he needs?
Chuck

[John Rudd]

I did a write up on the Sieg variant when I changed to TR bearings.......(use the search facility..)

But my machine didnt have the dreadbox gearbox but effectively the changes are the same....You need to shorten the spacer to accomodate the extra 'thickness'of the TR bearings...Alu...is the way to go..

[SLM]

If you find out exactly what you need, and can provide dimensions or better yet, a drawing, I'll make you one out of aluminum, or Delrin. You pay the post.That is if no one close to you steps up.
Any Real Bull owners out there that can tell SLM what he needs?
Chuck

Hey Chuck,

Thanks a ton!  If needed, I'll take you up on that!   

I'm hoping someone here has done this on one of these.  They are extremely similar to the SEIG lathes but from what I understand there are a few differences.  If it helps anyone it's the same lathe sold by Big Dog Metal Works here:

http://www.bigdogmetalworks.com/productcart/pc/viewPrd.asp?idproduct=779

EDIT:  John, thanks, I'll try and find it.  I've probably read it more than once already!  LOL!  If all that is required is shortening the back spacer I can probably muck my way through.

[John Rudd]

here's the link.....

http://madmodder.net/index.php/topic,6664.0.html

[SLM]

Thank you for the link.  I had read that through before but to be honest really didn't pay it much attention.  Your internals don't look like mine so I guess I doubted it would apply.  Now that I think about it some more I guess it doesn't matter if the spindle gear is one piece (what mine has) or two with a spacer like yours.  They're both still driven gears. 

I'm guessing the only way to know for sure if the internal spacers are going to have to be trimmed / lengthened is to try it and see.  The one common is the back spacer needing to be shortened.  I guess it's time to start modding!

[Stilldrillin]

Here's my experience.....   http://madmodder.net/index.php?topic=1292.0

(Don't miss the link, 4th line down).

I didn't change anything internally. Just slid the spindle out, removed the old bearings, and fitted the new!

The only mod, is to shorten the rearmost spacer, by a couple of mill, or so. This can be done easily, (carefully), in the lathe without the spacer, or nuts, in place.

Hope you don't find you have wobbly nut syndrome........ 

After rebuilding, machine new a spacer from steel or alloy.     http://madmodder.net/index.php/topic,7643.msg81872.html#msg81872
This gives much improved performance. 

David D

[velocette]

Hi SLM
Taper Roller Bearings are 17.25 mm on the inner race  as opposed to 16 mm on the ball bearing.

"Stilldrillin" has posted the link to the proper way to remedy any problem.

Eric

[John Rudd]

Hi SLM
Taper Roller Bearings are 17.25 mm on the inner race  as opposed to 16 mm on the ball bearing.

"Stilldrillin" has posted the link to the proper way to remedy any problem.

Eric

Indeed, the only way to set the preload with the newly fitted taper rollers is to fit a metal spacer replacing the orig plastic one.....

As I did on my Sieg.......

Only issue there is, is in cutting the slot for the key.....and and my method is shown in the posted link...

[SLM]

Thank you all!

David, I saw your story.  That's some nice work.  Do you happen to know the thread on the back nuts?  As I'm in the US my lathe is for standard threads but It's my understanding that I should still be able to get "workable" metric threads at least in a few combinations.  I could then (maybe) thread up an aluminum bar and do the face truing on my nuts one at a time?

John, it looks in the picture like you used some sort of cutting tool in a boring bar holder and basically "drug" the key way in?  My internal plastic spacers are going to have to stay, I have no way to make new ones right now and if I never have to take the head back off, it'll still be too soon but I'll most likely do the back spacer out of aluminum.  I do like Davids notch idea.  I could cut that with a Dremel too as I'm thinking it doesn't have to be very precise.

 

Bolstered by reading that this wouldn't be too bad I went last night to the local auto parts store and bought the two bearings!  Timkin branded, one made in France, the other in Poland.

I bolted my shaft vertically to my other work bench and had at reducing the diameter of the shaft for a sliding fit for the back bearing.  I had to do it old school with sand paper and shoe laces but it seems to have come out darn near perfect.  I can just slide the bearing on.  If it's a little cocked it won't go... at all, but get it square and it slides on and will move fairly easily but not fall on.  That took hours!

Which leads to this question...  Do I have to do the same for the front bearing?  I think I read somewhere that it is actually better if the front is still a press fit?

2
EDIT:  I ended up doing the front of the shaft for a very tight sliding fit.

[John Rudd]

John, it looks in the picture like you used some sort of cutting tool in a boring bar holder and basically "drug" the key way in? 

I used a boring bar with a cutting tool of the correct size to basically 'slot' the keyway by moving the saddle back'n'forth.....

[Stilldrillin]

Hi SLiM.
Thanks for your kind comment.   

The mandrel measures up at 27mm dia x 1.5mm pitch.  You might manage, with 1.078" x 16tpi.

Do the nuts have a wobble, when in place? I've come across several other Real Bulls with the affliction....... 

David D
 

[andyf]

For the thread, try the neat little calculator for minilathe threading set-ups at Little Machine Shop.
http://littlemachineshop.com/Reference/change_gears.php
LMS is biased towards Seig lathes, but the gears for Real Bulls are just the same.

Put 1.5 in the Desired Thread box, click the button for mms and then Calculate. Scroll down for the results, which will show various option to get you to 0.06% error. That's negligible over a short distance. 

The diameter should be 27mm, which is 1.063" if you only have an inch micrometer. Life will be easier if you start with stock a bit under 27mm - reduce by 0.15mm or 0.006", which will give perfectly adequate thread engagement for a mandrel. Don't remove the mandrel from the chuck after threading it, to preserve concentricity when you try the nuts on it to see if the end faces need skimming true.

Andy

[Stilldrillin]

27mm = 1.063", Andy? 

Yes! 

Time I got a new calculator..........   

David D

[SLM]

Hi SLiM.
Thanks for your kind comment.   

The mandrel measures up at 27mm dia x 1.5mm pitch.  You might manage, with 1.078" x 16tpi.

Do the nuts have a wobble, when in place? I've come across several other Real Bulls with the affliction....... 

David D

You're welcome!  Some day I hope I can do cool stuff too!  Right now I just want my lathe back together, LOL!

I have to admit, I don't know if they wobble.  If they do, it probably isn't too terrible.  I didn't spend too much time watching them but I didn't notice anything so... I'll pay more attention when it goes back together.  I ordered a spare from LMS in case one is really bad or I screw up trying to fix it.  I'll give them a good look when it's back together and most likely true them up no matter what.  It can't hurt right?   

Oh, from your experience thread there's a line that says "I have given it some (comparative) welly, using a 45dgr tool into a piece of 7/8" steel bed iron......  What's "welly" mean?  I'm still picking up some of the more, um.... non-American English terms but I'm getting there!   

For the thread, try the neat little calculator for minilathe threading set-ups at Little Machine Shop.
http://littlemachineshop.com/Reference/change_gears.php
LMS is biased towards Seig lathes, but the gears for Real Bulls are just the same.

Put 1.5 in the Desired Thread box, click the button for mms and then Calculate. Scroll down for the results, which will show various option to get you to 0.06% error. That's negligible over a short distance. 

The diameter should be 27mm, which is 1.063" if you only have an inch micrometer. Life will be easier if you start with stock a bit under 27mm - reduce by 0.15mm or 0.006", which will give perfectly adequate thread engagement for a mandrel. Don't remove the mandrel from the chuck after threading it, to preserve concentricity when you try the nuts on it to see if the end faces need skimming true.

Andy

Thanks for the link Andy.  I now have it bookmarked!  I accidentally found it one other time and forgot.     I'm sure it will come in handy at some point!

I think I have some 1.250" (31.75mm according to Google) aluminum bar here somewhere that should work out for this.  I'll turn it down and have at it at some point.  Thanks for the tip on leaving the mandrel in the lathe.  The truer the better I'm sure.

After that I'm going to see what I can do about making an aluminum back spacer.  I don't have anything with a large enough outer diameter here but the next time I order material I'll be sure to get some!

[andyf]

....a line that says "I have given it some (comparative) welly, using a 45dgr tool into a piece of 7/8" steel bed iron......  What's "welly" mean?  I'm still picking up some of the more, um.... non-American English terms but I'm getting there! 

It means he's worked them (his taper roller bearings) hard, SLM. I think the expression might(?) have come from motoring slang, with the idea of a foot, clad in a Wellington boot (or gumboot), being pressed hard down on the loud pedal (or accelerator), and have evolved into the sense of using some force; the expression is often used when hammering things, as in "Give it some welly". Wellington boots are frequently abbreviated to "wellies" over here.

Considering that our countries went their separate ways well over 200 years ago, it's remarkable how well we can generally understand one another!

Andy

[SLM]

Thanks!   I pretty much thought it meant something like that, just wanted to be sure!  Loud pedal I understand.  I spent almost 15 years working on and as a crew chief on a dirt track race car.  Good times!  In the garage it was usually "Hit it like you mean it!" when referring to using a hammer on something.  Or, "when in doubt, hit it with a hammer.  If that doesn't work, get a bigger hammer!"

And yes, fortunately English is fairly understandable on either side of "the pond".  Some of the expressions get a bit confusing here and there, heck that happens from different parts of the same country, but I'm going to try and remember "Give it some welly".   

I have the headstock cleaned up and both bearing races installed.  The parts should be here in a couple days.  I ordered the two smaller roller bearings for on the speed change shaft while I was at it.  One had a bit of a grind to it.  I don't know if it was bad from the factory or if it got buggered up when the gears went.  They aren't very expensive and it's all apart so this seemed like the time to change them.

Hopefully I can remember where all the parts go and start putting it all back together this weekend and start making some chips again soon.   

[SLM]

I received my metal gears today and cleaned them up. I'm distraught over the quality of the teeth on the small end of the intermediate gear.  Are they all this bad? I'm worried they are going to break or destroy themselves under load. Or am I concerned over nothing?

[lordedmond]

Send em back they look bad

looks to me as though they are full of porosities and junk


just my opinion other may say OK


Stuart

[andyf]

Seconded, Stuart. I wonder if this is a rogue set which keeps being returned, but the seller keeps sending out again in the hope that someone will accept them.

If bought by Ebay or Paypal, start a dispute if you can't get them replaced, or a refund.

If you bought them from Little Machine Shop, I'm sure Chris Woods will be more than happy to replace them.

Andy

[SLM]

Thanks guys! If this was "normal" I wasn't going to sweat it.

I called LMS and Chris is going to send me a new gear.    Back to waiting a bit but better safe than broke down again!

[picclock]

Had the same poor quality gear issues with mine.

http://s917.beta.photobucket.com/user/picclock/media/7x14%20Real%20Bull%20mini%20%20lathe/minilathe%20headstock%20rebuild%20info/DSC02445.jpg.html?sort=3&o=0

Having said that I've used and abused it a lot since then and it all seems to hold up well.

Taper Bearings are definitely a major improvement - especially with large items which stress the machine.

http://s917.beta.photobucket.com/user/picclock/media/DSC02458.jpg.html?sort=3&o=11

Really could have done with a lager lathe for that one

Best Regards

picclock

 

[SLM]

Hi SLM
Taper Roller Bearings are 17.25 mm on the inner race  as opposed to 16 mm on the ball bearing.

"Stilldrillin" has posted the link to the proper way to remedy any problem.

Eric

Hey guys!  I'm working on the back aluminum spacer but a bit stuck on the length. If the tapered rollers are 1.25 mm longer than the balls am I right that my new spacer should be 2.5mm shorter than the factory plastic one is?

Edit: The factory one is 31.75mm so 29.25mm?

Thanks!

Edit again:  I couldn't wait, LOL!  The length seems like it's just fine, my aluminum is too small though.  It's 1.25" and after I put a 1.105" hole in it there isn't much wall thickness.  It's so small on the OD that it fits into the taper on the back of the bearing.  I'm going to have to get something with a larger OD and make another one.

Still curious what length you gents cut yours to.