Old horizontal mill, RPM's

1BadDart · Jul 28, 2020

A few months ago I purchased a small yet to be identified horizontal mill https://www.practicalmachinist.com/.../small-old-horizontal-milling-machine-378617/. It appear to be similar to a larger Cincinnati that is in another thread on this forum.

I have a question on spindle rpms. Are these spindle speeds in the correct range? It currently has a 2" pulley on the motor. If I use a 1 1/2" drive pulley I can reduce the rpm's by 25%.

1-216 rpm
2-352 rpm
3-572 rpm

With the back gear engaged.
1-40 rpm
2-65 rpm
3-105 rpm

Thanks, Justin

Rudd · Jul 28, 2020

What do Hugh Hefner's bedroom slippers smell like?
Depends.

What you are cutting and the diameter of the cutter tell you what RPM to use. As it is, you are good for a 7" dia cutter in low carbon steel, for example. I would not think you need slower speeds (assuming HSS cutters).
Play around with this and see what you think.

Speeds & Feeds - LittleMachineShop.com

1BadDart · Jul 28, 2020

Thanks Rudd, yes the cutters I have now are HSS.

I see you're in Savanna, my 69 Dart came from there about 15 years ago.

marka12161 · Jul 28, 2020

1BadDart said:
A few months ago I purchased a small yet to be identified horizontal mill Small old horizontal milling machine?. It appear to be similar to a larger Cincinnati that is in another thread on this forum.

I have a question on spindle rpms. Are these spindle speeds in the correct range? It currently has a 2" pulley on the motor. If I use a 1 1/2" drive pulley I can reduce the rpm's by 25%.

1-216 rpm
2-352 rpm
3-572 rpm

With the back gear engaged.
1-40 rpm
2-65 rpm
3-105 rpm

Thanks, Justin

Seems about right, My Kempsmith 1G (gear head) is I think a 1930s design and top spindle speed is 575 RPM. Low end might be as low as 15 RPM. I also have a light duty V-head which has a 1:4 speed increase for small cutters

Rudd · Jul 28, 2020

1BadDart said:
Thanks Rudd, yes the cutters I have now are HSS.

I see you're in Savanna, my 69 Dart came from there about 15 years ago.

And my first wife (RIP) was driving a 69 Dart when she picked me up hitch hiking long about 1977.

The smaller pulley might not have enough wrap and be prone to slipping.
I have a horizontal about that size, the big cutters are a bit much, the wide tooth spacing on many makes for too much impact.
The advice I was given on setting feeds - crank it up till the machine starts jumping, then back off a bit. I don't do quite that hard though.
The table auto feed is likely to not be able to stand up to as much cut as the machine can take. Don't ask how I know this.

1BadDart · Jul 28, 2020

I'll probably never use this one very hard. It's all manual, the only auto feed will be my hands. LOL

Limy Sami · Jul 29, 2020

Those speeds look pretty good to me, ...it's a small machine so you won't be running big dia cutters or hogging so I don't think you need go slower.

1BadDart · Jul 29, 2020

Thanks guys.

This little machine is pretty keen. I only gave $200 for it, three end mill holders and the clamp set. It had a 4" drive pulley when I bought it and a buddy of mine suggested I slow it down. Also, I've bought a 4" tilting Palmgren vice for it.

Not really sure what I'm going to use it for but I like tinkering with this kind of stuff.

JST · Jul 29, 2020

Limy Sami said:
Those speeds look pretty good to me, ...it's a small machine so you won't be running big dia cutters or hogging so I don't think you need go slower.

Dunno, one of the mills here is a lighter-built one than that, and I run slabbing cutters on it, such that I have to use an overarm brace to the knee. Slow speeds are plenty useful, although I'd agree that 30 to 40 RPM is good enough.

Big diameter and "hogging" is relative, I can get max a 5" on mine, and have used one before. Hogging is another issue, You probably cannot bury a 4" cutter in the work just on a power basis, at least I'd not try it, the feed would need to be practically a "rubbing cut". But a big diameter can finish an entire side in one pass, with a lighter cut.

Rudd · Jul 29, 2020

Sheldon 0 in back gear with a 4" wide slabber will take .1" of cast iron. The feed drive won't, well, will maybe for a short while before it eats the worm.
His mill looks about the same as my Sheldon.

JST · Jul 29, 2020

Oh ja, the feed may be the limit, does not go slow enough, or can't take it. That is not so different from burying a 4" x 3/8" cutter in the work, considering the actual depth you can use out from the arbor.

But large cutters and slow speeds have their uses, as I said, one pass finishing if you do not need a deep cut. That 4" slabber might do fine in two 0.050" cuts and not break the feed.

Most of those slabbers are high helix, and have a surprisingly low feed force required.

1BadDart · Jul 30, 2020

I need a arbor for the mill, #3MT drive end, 1/2" on the support end, up to 12" long from the large diameter of the taper to the end of the support end. I can buy a 3MT spindle on e bay but it has no support end.

If anyone knows where I can find one please let me know.

Thanks.

JST · Jul 30, 2020

1BadDart said:
I need a arbor for the mill, #3MT drive end, 1/2" on the support end, up to 12" long from the large diameter of the taper to the end of the support end. I can buy a 3MT spindle on e bay but it has no support end.

If anyone knows where I can find one please let me know.

Thanks.

You generally find that sort of unicorn on your lathe.

My small mill takes 3MT, and I made several arbors for it. I used 4140PH, but you can use 1144, or just plain CRS if you want, it won't wear quite as well.

1BadDart · Jul 30, 2020

JST said:
You generally find that sort of unicorn on your lathe.

My small mill takes 3MT, and I made several arbors for it. I used 4140PH, but you can use 1144, or just plain CRS if you want, it won't wear quite as well.

I'm not that skilled with my lathe yet. I've thought about buying the one off e bay, boring the threaded end and making a stub shaft to press in it. Then I could use the support arm.

Rudd · Jul 30, 2020

you sure it is MT and not B&S? B&S was much more common on mills.
Michigan Drill

thermite · Jul 30, 2020

1BadDart said:
I'm not that skilled with my lathe yet. I've thought about buying the one off e bay, boring the threaded end and making a stub shaft to press in it. Then I could use the support arm.

Burke #4 is similar - #9 B&S, but still uses only a stub 60-degree center in the over-arm. One can make an adapter to supply that centre-point functionality set into an existing over-arm bore for a bushing and not need to patch it onto just the one arbour at each go.

Finding - or creating - a center divot in any of MANY arbours thereafter is just not all that hard.

And you still have the choice, going forward.

JST · Jul 31, 2020

1BadDart said:
I'm not that skilled with my lathe yet. I've thought about buying the one off e bay, boring the threaded end and making a stub shaft to press in it. Then I could use the support arm.

That's how you GET "that skilled". You DO whatever comes up that needs doing, as long as you have time. Study up a bit, and have at it.

Weren't nobody born knowing how to do this stuff.

thermite · Jul 31, 2020

JST said:
That's how you GET "that skilled". You DO whatever comes up that needs doing, as long as you have time. Study up a bit, and have at it.

Weren't nobody born knowing how to do this stuff.

Takin' that a step further.. yah set up with the material to-hand to make, say six. Not two. Not just the one.

"Highly likely" (or so the grown-ups whisper, I'd not be one to KNOW this, "directly" would I?)....you will screw up one. If not two.

NOW .. yah still have four good un's and the pride in having FINALLY SORTED the problem that lets yah grin and keep the faith, going forward, future challenges, better, faster, lower scrap rate etc..

Not 50% loss. Or 100% loss.

That messes up yer schedule, aggravates yer mind.. and kinda takes the wind outta yer confidence.

Cheating? Dambetcha!

You'd have to know human nature? Or maybe only "learning curves?"

"The Regiment" nailed it bestest and simplest:

"Who dares, wins!"

projectnut · Aug 2, 2020

1BadDart said:
A few months ago I purchased a small yet to be identified horizontal mill Small old horizontal milling machine?. It appear to be similar to a larger Cincinnati that is in another thread on this forum.

I have a question on spindle rpms. Are these spindle speeds in the correct range? It currently has a 2" pulley on the motor. If I use a 1 1/2" drive pulley I can reduce the rpm's by 25%.

1-216 rpm
2-352 rpm
3-572 rpm

With the back gear engaged.
1-40 rpm
2-65 rpm
3-105 rpm

Thanks, Justin

Do you know what type of bearings are used in the spindle? Most machines of the flat belt era use plain bearings as opposed to deep groove ball bearings or tapered roller bearings.

Looking through publications for different machine tools most flat belt machines have spindle speeds between 10 and 500 rpm's. My Seneca Falls 10" lathe is of that era and has a speed range of 18 to 340 rpm. Their larger machines have a speed range of 10 to 471 rpm.

1BadDart · Aug 3, 2020

Thanks guys.

I just recently picked up a threading dial and don't have the tooling yet to cut threads. The plan is to convert it over to a AXA wedge toolpost and tool holders. As of now I'm using the original lantern tool post with Armstrong tool holders.

In time as I get more tooling and more experience I'll tackle more complex projects.

Justin

Old horizontal mill, RPM's

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