Author Topic: Fitting linear ball rails to a lathe cross slide.  (Read 4274 times)

Offline tonyfoale

  • Jr. Member
  • **
  • Posts: 14
  • Country: es
    • MotoChassis - Source for the chassis design book & software.
Fitting linear ball rails to a lathe cross slide.
« on: December 18, 2023, 03:07:44 PM »
I have been a member here for several years but to be frank I had largely forgotten it and I do not recall posting previously.  This is to change that. 

I race classic motorcycles and I make tools to make tools to make parts for the bike.  This post is about one such tool.
I want to make some camshafts and $1M for a Landis CNC grinder is a little out of my range as well as space to put it.  So I am modifying my lathe for the purpose.  I have previously converted the lathe to ball screws and electronic control which has improved accuracy in general but to get the ultimate in resolution and accuracy I am now converting the cross slide to linear ball rails.  To make the cams, the cross slide will be controlled by software and the position will be tied to the spindle position via a rotary encoder.  A grinding head will be fitted to the rear of the cross slide.

I made a quick video as an introduction describing how it will be done.  I am currently waiting for the linear rails to be delivered. I will make other follow on videos showing the actual progression of the work.  Overall it is a surprisingly easy conversion.
Here is a link to the video


and here is a link to a playlist with details of the previous mods to the lathe



 
 
 

   
  This is the grinding head.

I have previously made a cam by using the X&Y movements on a CNC mill but this is unsuited to longer cam shafts.
 
   

Offline BillTodd

  • Hero Member
  • *****
  • Posts: 1112
  • Country: 00
  • Colchester Essex (where the lathes were made)
Re: Fitting linear ball rails to a lathe cross slide.
« Reply #1 on: December 19, 2023, 11:32:57 AM »
Cast Iron/steel is a better material for the job Tony.  Mild/Tool Steel stock has poor internal damping so tends to 'ring' more.

Interesting mod . BTW a few years ago (maybe decades) there was an excellent article about the nuances of cam grinding on the Practical machinist  forum by a very experienced machinist . I'll see if i can find it

a modern one:https://www.practicalmachinist.com/forum/threads/camshaft-grinder.416979/

can't seem to find anything in the archive :-(
Bill

Offline tonyfoale

  • Jr. Member
  • **
  • Posts: 14
  • Country: es
    • MotoChassis - Source for the chassis design book & software.
Re: Fitting linear ball rails to a lathe cross slide.
« Reply #2 on: December 19, 2023, 03:04:37 PM »
Bill,
Thanks for the link.  I had seen it previously.  The rocking cradle type of cam grinder has been the standard design for decades prior to the introduction of CNC grinders.  The net is full of DIY examples of rocking cradle designs, some very good and some very iffy.
If I have problems with my own CNC efforts then I can fall back on using the X&Y axis of a CNC mill as pictured in my initial post.
My only concern is that there are two direction reversals of the slide per cam revolution so backlash is a factor but I shall spring load the slide to avoid load reversal.