Modifying Boxford

[Niels Abildgaard]

It is my hope to make an old Boxford a little better.
The lower half of picture shows the Boxford arrangement more than 60 year old and with a spindle that will alow 20mm through.
The upper half shows my modifications to headstock.
They are few.
The two grease dams or traps close to bearings will be opened from 45 and 38.9 mm to 50.1 and 60.1 for the new spindle.
I bougth two new NTN spindle quality 32910 and 32912 bearings in France for 100 €.
The small one 72/50/15 mm goes into existing rear bearing hole.
The 85/60/17 mm one needs a new seat.
Existing front hole is 76.2mm and will have to be enlarged to 85mm cirka 12mm deep.
I can probably do it on a milling machine to within 0.1mm.
Now comes the reason I am asking for help on this forum.
Obviously I want the new bearing seat to be absolutely concentric with with the existing two and it somehow looks like grinding valve seats in IC engines.
Any ideas or knowledge of existing tooling that will do?

[Jasonb]

Usual method for in situe reboring is to use the opening at one end to support a bearing and find a way to support the shaft at the end you want to work on. You then have a shaft with a cutting tool much like a between ctrs boring bar that can be rotated and also slowly advanced into the hole. may be possible to use the lathe itself to drive the bar and the carrage to feed with.

I'll did out a photo of a cylinder being done later.

[steamer]

Neils

All this can be done...with some ingenuity.

Besides Jason't comments...which is the way I would do it if I had to .....you could get another Headstock and modify it perhaps between centers in this lathe.    You could use the saddle to push the donor headstock down the ways if the ways aren't too worn already.  Or   mount a big knee to the cross slide and mount the headstock to the knee


....that said and at the severe risk of being labeled the pot.......     Are you sure you want to?

Would it be more efficient to just get another lathe?   With a bigger HS bore?

[Jasonb]

Not sure if you will be able to see these

http://www.tractiontalkforum.com/picture.php?albumid=1064&pictureid=20784

http://www.tractiontalkforum.com/picture.php?albumid=1064&pictureid=26065

http://www.tractiontalkforum.com/picture.php?albumid=1064&pictureid=26069

The video shows it better, angle drive motor providing feed, gut buster drill and speed reducer turning the bar

[youtube1]https://www.youtube.com/watch?v=DdqCorgLANs&app=desktop[/youtube1]

[Niels Abildgaard]

Thank You for pictures,videos and advice .

It is just a game where I try to devellop a method for bringing Boxfords into this century low cost.
VFD means no backgear is needed.
Electronic leadscrew means no spindle gear.
Bigger and stiffer spindle .
Constraint is it shall be possible without removing headstock and have some swiss do expensive things to it.
My present Boxford (Worlds best Southbend offspring) can be twisted by underlying granite to turn paralel within my measuring ability.
That means that if I can modify the front bearing hole so that a new 85/60/17 bearing sits absolutely concentric with the original Boxhole everything will be  OK.Existing hole is 76.2mm dia and shall be oppened to 85mm for a depth of ca 10-12 mm.
I have got another Headstock to experiment with but aim is to be able to do it on site.
I dream of having a camper for me and dog and then travel around making Boxfords usefull.
Have brain and tools.
Will travel.

[Niels Abildgaard]

Jason I can see the video but not pics
Another picture of headstock