Why didn't you use the original X screw mount extension concept? Not the most rigid setup to have the bearings exposed like this and in an aluminium block. It does look creative though

Dan

1. my slide comes all the way out over the motor so unless i mount the motor backwards ill never have the room.
2. the original mount is way to small for the new bearings.

I disagree as long as you have good bulk on ether side of the bearing your just not going to apply enough pressure to the bearing collar to get it to deflect, the inside has 200mm of cast iron slide and the outside had 30mm of Ali, im exposing probably less that 1/3 of the bearing which is hardened steel, the motors will give out or the belts will break before there is any significant deflection.

comments anyone with more experience?

cheers

Hi,

1. my slide comes all the way out over the motor so unless i mount the motor backwards ill never have the room.

I know. I think it is worth considering.

2. the original mount is way to small for the new bearings.

Was suggesting to use the concept. Not the same mount.

I disagree as long as you have good bulk on ether side of the bearing your just not going to apply enough pressure to the bearing collar to get it to deflect, the inside has 200mm of cast iron slide and the outside had 30mm of Ali, im exposing probably less that 1/3 of the bearing which is hardened steel, the motors will give out or the belts will break before there is any significant deflection.

comments anyone with more experience?

cheers

It all comes down to the final rigidity of the machine. Motors and belts don't give you rigidity. Frame construction, mounts, bearings, slides and screws do. Your setup may and probably will work fine, but will be far less rigid than a proper steel mounting blocks. Depends on what you intend to be using the lathe for I guess.

Dan

 

Not the most rigid setup to have the bearings exposed like this and in an aluminium block.

It seemed like you were saying that by enclosing the bearing the machine will be more ridged, yes i guess in theory by adding 100 grams of extra metal it will be more rigid, practically though if rigidity is a problem ill add 100kgs of epoxy granite.

1. my slide comes all the way out over the motor so unless i mount the motor backwards ill never have the room.
2. the original mount is way to small for the new bearings.
I disagree as long as you have good bulk on ether side of the bearing your just not going to apply enough pressure to the bearing collar to get it to deflect, the inside has 200mm of cast iron slide and the outside had 30mm of Ali, im exposing probably less that 1/3 of the bearing which is hardened steel, the motors will give out or the belts will break before there is any significant deflection.

I admit I was a bit startled at first when I saw the way the bearing housing was cut away, but ...

First of all, the driving/cutting forces will be along the axis of the leadscrew, and the amount of metal used seems adequate for the size of the lathe. The inner aluminium support is not fat, but it is backed up by the steel body. The outer aluminium plate is quite fat enough. The holding bolts are large (bigger than the originals?). This is not a production machine for car axles after all.

Second, the forces due to the drive belt are all downwards, not upwards. The bearing is well supported underneath.

Third, the bearing itself is quite a solid unit and does not look as though it would flex very much :-)

So while it is hardly conventional, I can't see too many reasons why the arrangement would not work.

My 2c
Cheers and Merry Xmas

Watching this thread develope has got me thinking of converting a Harrison M300 to cnc. I have a 3hp Boxford 240 cnc lathe at the moment, but now and again i need a bit more z movement than the slant bed boxford will allow, and the harrison M300 sat in the back of my storage would make a lovely straight bed cnc.

I admit I was a bit startled at first when I saw the way the bearing housing was cut away, but ...

You got to do what you got to do to make it work, the bearings are still sealed and well supported (32x10mm each)

So while it is hardly conventional, I can't see too many reasons why the arrangement would not work.

Were going to find out pretty soon eh!

Never said it was not going to work It's just not the common way to do this - press fitting a bearing in a sectioned housing...

Yes, we'll know soon how it works out. I guess no one has done this before, so your experience may help others. If anything, the biggest problem is going to be when using a 3mm part-off tool in alloy steel 30mm in diameter.

Dan

I think it will be just fine all considering. Post adjustment and preload of the bearings just a few drops of crazy glue will make that bearing an intregal part of the mounting.
Retrofits require trade offs and in this case not reducing the depth section of the above cross slide is probably to the better.
Rich

Retrofits require trade offs and in this case not reducing the depth section of the above cross slide is probably to the better.

Agreed, its not like this is a production machine running 8 hours a day... 

Its looking great and I know it will work great too.  Yours skills are good, so if you need to make additional modifications you can, this is the first pass, you my need to do a second pass as you learn how it works.  Just because you make something, doesn't mean its final.

JH