PM BS-0 Dividing Head on PM-25 Mill: Comments, Photos, and Questions

[devils4ever]

There seems to be a lot of interest here on the BS-0/1 dividing head on various sized milling machines. I bought the PM BS-0 dividing head recently and I thought I'd share some and ask some questions as well.

To me, I think the BS-0 dividing head is the right size for my PM-25 mill. I don't think I'd want to go any bigger. As it is, when I put the chuck vertical, there isn't lot of clearance left. Bigger might give no room for parts and cutters.

Be careful when using the tables in the manual that came with it. There are errors in there on settings for various divisions. I calculate everything manually and cross-check it with the manual.

Here's some photos showing the size relative to the mill's table. I'm cutting some flutes on some 5/8" (~16 mm) stock here.





I needed to use an extra long cutter to clear the chuck jaws. Also, this is the first time I've used the tailstock. I'm assuming that the large SHCS on the bottom is to remove play in the center and the smaller screw on the top is to lock everything down? Is that correct? Getting everything aligned is a little time consuming since the screw pushes the center backwards (along Y axis). Plus getting the height right is a little tough as well using the two large hex head bolts. But, I was able to get it within 1 or so thou over the entire 4-1/2" length of cut. Overall, I'm very pleased with this dividing head.

I created a spreadsheet to calculate the Y and Z position of the end mill based on stock diameter, end mill diameter, and depth of cut. I cut at the 45 degree position.

 

[Bi11Hudson]

Any machine tool is sized relative to the other tools in use. A BS-1 is larger than a BS-0. I have a B&S indexer smaller (lower profile) than a BS-0. But if I faced larger work, I would need a larger mill as well as a larger indexer.
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[koenbro]

Very helpful as I was just debating whether to buy the dividing head or a rotary table and went with the latter, because of the very same concerns that there isn’t enough of the z-axis to accommodate it.


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[Alcap]

Thank you for starting this thread . I have a Clausing 8520 and thinking of a dividing head like yours . I bought a way too large 10” Phase 2 rotary table and tail stock at a price I couldn’t pass but because of the size and weight have only used it a few times on my Jet 15 mill drill . When setting yours up are there locating keys on the bottom of the dividing head and tail stock ? If not how do you set them in the same centerline ? Maybe that’s not an issue I’m just trying to learn . Al

 

[devils4ever]

koenbro: Yeah, I debated the same thing and decided to get the dividing head. I may still buy a rotary table in the future. They are more flexible with any number of divisions possible.

Alcap: Yes, there are locating keys on the bottom as shown. Unfortunately, the keys are about 0.630" (16 mm) in width which doesn't fit the slots in the PM-25's table. I may make some in the future. So, I run an TDI along the top and and side of the chuck to get it close. Then, I put in some drill rod (or the workpiece) in the chuck and run the TDI along that.