[4]

Rear Tool Post for Colchester Bantam Lathe

[3]
[10] Like what you see?
Click here to donate to this forum and upgrade your account!

SnakeyJ

H-M Supporter - Silver Member
H-M Supporter - Silver Member ($10)
Joined
Oct 27, 2018
Messages
72
I'm looking to add a rear tool post to my Bantam for parting, grooving and threading form tools and looking for any advice/comments before marking and cutting.

The Bantam cross slide does not have T slots, but is already drilled and tapped for a T slot plinth and rear toolpost (illustration from lathe manual):

1565787358108.png

While I could replicate this, it would be nicer to fit Dickson T1/S1 tool holders and I have a spare QCTP, which could be mounted though think it might be a little bulky. I'm planning to make a raised plinth (5" x 3.5" x 2" wdh) which will screw down across the rear of the cross slide and matching the height and T slot cut in the compound. This will secure down with six 5/16 x 18 UNC bolts using the existing threaded holes (capped with grub screws here to keep the swarf out):

1565796463813.png
Not sure what the two tapped holes and two untapped holes were for, but seem to be common with other Mk1 Bantam cross slides.

With the plinth and tool post I should still be able turn just over 6" diameter and comfortably clear a 5" chuck - though always have the option to remove it if necessary.

I have two pieces of Meehanite (GGL25CA), the larger cut to machine the plinth and the offcut is sufficient to make a single Dickson QCTP or a couple of extra tool holders if needed.

1565797300449.png 1565797337026.png

1565797381697.png 1565797408538.png

Time for a drawing or three, but probably just roughs on paper till I get a clearer idea as my SketchUp/FreeCAD skills are rather dire!
 

brino

Active User
H-M Supporter - Gold Member ($25)
Joined
Jan 2, 2014
Messages
3,670
It looks like you have many good ideas and options.

Sorry, no advice here.......just stopped by to say I am "watching" this thread for more good ideas.
I would like to add a rear tool post to my SouthBend 9", but the cross-slide has a contoured top.
I'd need to drill and tap, and/or mill a flat, or replace the cross-slide completely.

-brino
 

ttabbal

Brass
Registered
Joined
Jun 12, 2017
Messages
904
One thing to consider is that the QCTP may well contribute to a lower rigidity in the overall system. How much this happens or matters might be debatable. I considered making mine adjustable, but decided against it for this reason. Mine is for parting only, so once cut to the right height, it doesn't need to be adjusted. However, it does make adjustment for the initial setup time consuming. :)
 

mikey

Active User
H-M Platinum Supporter ($50)
Joined
Dec 20, 2012
Messages
5,537
Another idea is to make a "plinth" that mounts in the rear and make tool holders for different functions like Chris Heapy and many others have done. Chris no longer has an active site but you can still see his implementation here. His stuff is inspired by GH Thomas and others but is very well executed.
 

SnakeyJ

H-M Supporter - Silver Member
H-M Supporter - Silver Member ($10)
Joined
Oct 27, 2018
Messages
72
It looks like you have many good ideas and options.

Sorry, no advice here.......just stopped by to say I am "watching" this thread for more good ideas.
I would like to add a rear tool post to my SouthBend 9", but the cross-slide has a contoured top.
I'd need to drill and tap, and/or mill a flat, or replace the cross-slide completely.

-brino
Thanks Brino : sure you will have seen this thread over on practical machinist, a good read, but expect the kits are expensive. https://www.practicalmachinist.com/vb/south-bend-lathes/machining-t-slotted-cross-slide-177054/
 

brino

Active User
H-M Supporter - Gold Member ($25)
Joined
Jan 2, 2014
Messages
3,670
Actually I had NOT seen the PracticalMachinst thread, I don't go there as often as I come here. Thanks.

I was aware of the Metal Lathe Accessories t-slot cross-slide kit.
It is not unreasonable $56 (https://mlatoolbox.com/S-4382.html).
(although the Canadian shipping at + $46 is abhorrent, I don't blame them!)

-brino
 

SnakeyJ

H-M Supporter - Silver Member
H-M Supporter - Silver Member ($10)
Joined
Oct 27, 2018
Messages
72
I was aware of the Metal Lathe Accessories t-slot cross-slide kit.
It is not unreasonable $56 (https://mlatoolbox.com/S-4382.html).
(although the Canadian shipping at + $46 is abhorrent, I don't blame them!)
-brino
That sounds like incredible value to me, even given the shipping. It does sound quite a job, especially getting the dovetail and gibs spot on. Surprised he managed all of this on the Sieg SX3 (with a quick dust with a work surface grinder for the final finish) - the finished result looks stunning.

The uneven and tapered profile is difficult, but perhaps it might be possible to take a different tack and retain the existing cross slide and mounting a t slotted plate on top, though not clear how much of the original casting could be ground back to bond/fix to. It would doubtless be a less satisfactory job and quite possibly end up being more expensive if you needed to get a one off/custom plate made up.
 

SnakeyJ

H-M Supporter - Silver Member
H-M Supporter - Silver Member ($10)
Joined
Oct 27, 2018
Messages
72
Three hours spent learning how to use FreeCAD.......

I now have a 3D model of the plinth, but yet to learn how to dimension and export this as a 2D technical drawing.

1565867734423.png

The mounting holes are approximately positioned drilled to 5/16" and will be counter bored for cap heads.

Now to add a model of the QCTP and practice my 3D CAD skills..
 
[5] [7]
Top