Countershaft for horizontal mill

[Shawn]

The Benchmaster mill came with both a horizontal setup as well as a vertical. The spindle speeds sem fine for the vertical mills but it's to fast for spinning the larger diameter cutters used in horizontal milling. My mill is strictly horizontal so I need to slow the spindle speeds down a bit. A few years ago I had planned to buy a 3ph motor and run it with a VFD, that still hasn't happened. The other day I realized I had everything I would need to build a countershaft and nothing but time to waste  


The bearings I had on hand had a smaller ID than the pulleys I had on hand so the plan is to turn some plugs for the ends of the spindle and then plug weld them in place. Because I turned the spindle between center I will be able to turn the plugs between centers to make sure everything stays concentric, that's the plan anyways. I'll leave enough sticking out that you will be able to cut of the welds and replace the bearing if need be, I doubt I will be the one cursing the weld job at that point anyways 





The motor was removed and will reside on the jack shaft. There will be an adjustable over camming mechanism for tensioning the CS similar to what you see on South Bend lathes. I am even going to paint the countershaft boring old grey to match the mill, even though I got a few cans of Chevy orange left 

I'll post a few more photos as things progress. 

P.s.  I should mention I used my own scientific method for calculating the final spindle speeds. It involves staring at things for a bit and thinking about what I was going to have for lunch, The answer I arrived at was... probably be good enough. I can mentor you on this method Tom, no need for a calculator and it's almost never what you expect it to be in the end so it keeps ya guessing 

[Mayhem]

(02-24-2015, 03:11 AM)Shawn Wrote: ...I am even going to paint the countershaft boring old grey to match the mill, even though I got a few cans of Chevy orange left  ...

Smart decision. Use the Chevy orange when you wish to speed things up. Grey or (even better) Ford blue is an appropriate choice when slowing things down

Nice job thus far.

[Shawn]

Slow progress but at least it's progress. 

[Sunset Machine]

If it helps any, mine goes from 15 RPM (back geared) to a screaming 300 RPM on the top end. I've been thinking of painting it, will go with Ford Blue.

A 6" HSS side cutter = 65 rpm
A 3" involute cutter = 135 rpm

and they are expensive. Go slow. I've made cutters from old leaf springs. Go slower.

[Shawn]

Thanks Sunset, I have decided to get a smaller pulley for the motor shaft and a larger one for the countershaft before the step pulley. I would be happy to have my lowest speed be around 60-70rpm, I think that would allow me to use all the size cutters I own in mild steel which is my goal for this conversion.

QUESTION: I have two options as far as I can see, make the entire countershaft assembly rotate on it's base to tension the mail drive belt or use a wide idler pulley to put tension on the mail drive belt. Most countershafts I have seen don't make use of a idler pulley, is there a reason for this? To me it would seem like having the countershaft assembly as ridgid as possible would transfer less vibration to the machine? Thoughts or suggestions are greatly welcome.

Shawn

[Shawn]

@Mayhem, Ha, just got it. I'm not much of a car guy (I drive a ford so we both know what that means, well you do at least : )

[Sunset Machine]

Nothing wrong with using an idler. My mill-drill uses two of them (stepped sheaves) to set 3 belts for 16 speeds. The idlers float, you loosen/tighten all the belts at the same time with a single clamp. Very easy.

My Logan lathe uses step pulleys and back gears like most, but the motor drives a 2 step flat pulley through a vee belt! The flat pulley allows shifting the belt while under tension. I don't like it much and just leave it in the low range.

[Shawn]

I couldn't think of any good reason not to use an idler either. I'm going to use a weighted idler pulley then that can be easily adjusted to follow the 5 speed changes.

Cheers
Shawn

[f350ca]

The only drawback I can think of, is that some v-belts don't have a smooth back. The idler may bounce and be a bit noisy.

[Sunset Machine]

That'd be it. I have a number of belts going bad - the backs peel off. So use shorter belts and idlers instead of long belts and tensioners. Here's a pic of the mill-drill, looks perfect for what you're doing. The brackets in the middle (wrapping the column) look like they're bolted down, but they're just loose and allowed to swing free. They support the idlers independently (floating) and the motor is mounted on a hinged plate on the left. Main spindle on the far right. 16 speeds.