Upgrade for Sherline Lathe Base

[Karl A]

As of yet, Sherline hasn't provided dimensions of the machined base on their website.

Here are some measurements that I took, in inches:

4400 Machined Lathe Base - 2024 series (44040)
- 26 3/8" long x 4 7/8" wide x 0.3612" thick (average, see below)
- thickness measurements, using Mitutoyo digital micrometer:

The top of the base has been machined; the bottom has not.
There is a not-threaded 0.257" diameter hole near each corner, located 1/2" from left/right edge and 1/2" from front/rear edge.
There are is a 10-32 threaded hole near each corner, located 1.0" from left/right edge, 1.0" from rear edge, and 0.97" from front edge. These might be for Rubber Feet w/screws (61100).

Machined Headstock End Mount (44020)
- 3.02" long x 3.02" wide x 2.50" thick
The base (44040) extends 1.22" to the left.

Machined Tailstock End Mount (44030)
- 2.00" long x 2.375" wide x 1.90" thick
The base (44040) extends 1.22" to the right.

The 24" Machine Lathe Base Assembly -2024 Series (44050) is 0.36" + 0.05" = 0.41" taller than my 24" Cast Lathe Base (44010). The 0.36" is the thickness of the base (44040). Note: I milled and filed the bottom of my cast base flatter, which reduced the height of my cast base by roughly 0.05".

One conclusion that I draw from they measurements is that if I decide to buy the end mounts and install them on a custom base (instead of 44040), then the custom base will need to be at least 3.02" wide by 23.935" long (26 3/8" - 1.22" - 1.22") to fit entirely under the end mounts.

 

[Forty Niner]

I received and installed the new machined lathe base on one of my Sherline lathes. I am pleased with the new base. The alignment of the headstock to the lathe bed assembly is much improved over the cast base. Previously, with the cast base, I spent much time trying to improve the vertical alignment of the headstock to the bed ways using shim stock.

 

[Choiliefan]

Any chance you can post a pic of lathe mounted to new base?

 

[Forty Niner]

My Sherline lathe mounted on new base. I've not attached it to the board yet. Just checking things out. Motor is not on because lathe was last used for threading.

The lathe sits about 3/8" higher with the new base.

 

[EricB]

Looks good! I can see it would be easier to keep clean.

 

[Karl A]

An indirect result of my ordering and receiving the new-for-2024 machined lathe base is improvement in the original cast base.

I set my lathe (minus the cast base) into the machined base, and saw that there is a very visible amount of space between the left mount, and the lead screw support and the lower, non-vee parts of the bed. After seeing that, I removed thick paint from my cast base to achieve visible spacing. The result was significant less vertical misalignment of the headstock spindle, and a significantly thinner shim to remove twist in the bed.

With both the cast base and the machined base, the vee of the bed sits in a vee bed in the base. I think that the vee of the base is slightly steeper (smaller angle of opening) than the vee of bed, resulting in the upper part of the bed vee contacting the upper part of the base vee. I think that the difference in angles of vee also allows the bed to rotate a little during assembly, to match the rotational-position-around-the-z-axis set by the flat surfaces on which the bottom of the bed rests in the base on the right side. I'm not sure that these two thoughts are correct.

I don't like the vee of the bed sitting in a vee in the base. It's a kinematic "prismatic joint" that theoretically provides movement in only one dimension, if it is machined perfectly or includes a gib. I looked for other kinematic mounting methods. I found a ball and a vee block online that I think can work, in two pairs. I think that one ball+vee block can be installed under the rear of the bed and inside the rear of the left base mount, and one ball+vee be can installed under the front of the bed and inside the front of the left base mount. One vee block can be oriented to prevent left-to-right movement of the bed, and the other vee block can be oriented to prevent front-to-back movement of the bed. The ball+vee pairs can also be used to hold the bed down in the mount. The height and z-axis-rotational-position of the bed in the left mount can be adjusted to match the height and z-axis-rotational-position of the bed in the right mount, using shims placed under the vee blocks.

I don't like the base of the machined lathe base. The bottom isn't flat; it rocks on my 80/20 platform. I prefer a base made from ground-and-milled, parallel-and-flat, 6061 aluminum blank, 24 inches long x 3-to-4 inches wide x 0.8-to-0.9 inch thick. For an 0.8-inch thick base, I would want to mill the left and right mounts 0.8 inch thinner. Such a modified version of the Sherline machined base would appear more similar to the cast base.

 

[Forty Niner]

I like the new mounting blocks. They fit really well. Like Karl, though, I would really like a thicker mounting plate for the blocks. I would like a much thicker plate, and possibly one from iron or steel instead of aluminum. But, having said that, I still prefer the new setup over the old one.

 

[Karl A]

... The alignment of the headstock to the lathe bed assembly is much improved over the cast base. ....

My measurements of spindle vertical alignment agree.

Here are measurements of rise of a headstock-spindle alignment bar installed on the spindle, across 2.75 inches from left to right (using a tenths dial indicator).

The parameters are the tightness of the screw that attaches the lead screw support to the base, and motor installed on or motor absent from the headstock.

cast base
screw loose, motor absent: -0.000,1"
screw loose, motor installed: +0.000,4"
screw snug, motor absent: +0.000,5"
screw snug, motor installed: +0.000,7"

machined base
screw loose, motor absent: -0.000,2"
screw loose, motor installed: +0.000,1"
screw snug, motor absent: -0.000,2"
screw snug, motor installed: 0 000,0"
screw tight, motor absent: +0.000,1"
screw tight, motor installed: +0.000,3"

I obtained these measurements today, with the lathe on my 80/20 platform. The cast base was scewed to the platform. The machined base was sitting on the platform.