How bad of an idea is it to cut structure out of my lathe base?

[Redneck_Sophistication]

I’m prefacing this as a bad, or st the very least not a great idea.

I’ve finally got a motor to install in my lathe that came without one.

tobarapprentice graciously provided me with a 3hp motor he had and I thought it was perfect, it’s a bit of a beast, but so is my lathe, it fits in the lower section/motor compartment but due to the opening between the upper and lower areas the belt needs to be on an angle and there is a web in the base that interferes.

Looks like I would need to cut out the majority of it to fit the motor at the proper location. Obviously this was made like this for a reason, but old iron tended to be over built. I guess steel was free back in the day lol.

Also found it odd that you need to remove the pulley of the lathe to install or replace the belts. :/

Looking from pulley

From the rear

Hole for belt

Needs to move over probably the width of the entire web

Pulley tight to housing

Lathe is a McDougal. Can’t find any info online about it.

 

[Mcgyver]

I don't think I would, for sure wouldn't use any sort of heat or grinding. It may work, but the downside (everything shifting and twisting a bit) is just too great. It looks like a solid likely very well made lathe, you wouldn't want to mess up. While CI is better than say mild steel, there can still be internal stresses. It won't move in a million years (or there abouts) in its currently equilibrium, but change that equilibrium by removing material and who knows.

 

[Tom Kitta]

Why don't you get a new motor for it? I assume it is a 3ph motor - these are plentiful especially in ON and dime (or with current inflation a quarter) a dozen.

 

[RobinHood]

I would not cut out anything.

What size motor pulley is that? Looks almost the same as the input shaft pulley (ore even bigger).

Is this a clutched lathe or direct drive?

 

[Scattered Parts]

What frame size and horsepower is the motor you are trying to install? Perhaps a lower hp motor would fit better. A smaller pulley and a 1750 rpm motor may be just what is needed.

 

[trlvn]

Lathe is a McDougal. Can’t find any info online about it.

It is not much, but this is some history at:

Page Title

Craig

 

[Redneck_Sophistication]

What frame size and horsepower is the motor you are trying to install? Perhaps a lower hp motor would fit better. A smaller pulley and a 1750 rpm motor may be just what is needed.

It’s a 3hp motor. Not sure the frame it’s quite large, obviously older.

As far as the pulley, it’s just what was on the motor when I got it. Smaller would have been on the cards.

There is not as many motors around as I’d thought. Sent a few feelers out on the usual scumbags again.

 

[Redneck_Sophistication]

It is not much, but this is some history at:

Page Title

Craig

That’s one of the pages I did find when I first bought the lathe.

Funny enough it was made in Galt Cambridge, so it’s come home. Just ten min away. I have thought to go to the town and see if there was any info in any sort of archive.

I have my doubts I’ll find a user manual for my lathe just kicking around lol

 

[Tom Kitta]

Its probably one of these motors from 1950s. It may not use current frame sizes.

In AB we have lots of motors around so in ON I assume there should be plenty more, especially 3ph.

 

[trlvn]

In your other thread, I believe you said it is a 115/230 volt motor. So single phase, right? If so, is it the start capacitor that it preventing you from mounting the motor where you really want it to go? I'm not a sparky but I believe you could extend the wires connecting the capacitor and mount it somewhere out of the way.

Craig

 

[Scattered Parts]

A significantly smaller frame size motor like a 56 would possibly fit in there. For a 3 hp motor they are around 6 to 7 inches in diameter . The motor you have appears to be a much larger frame size like a 182 or 213. These are significantly larger than the 56. Where on the casting of the lathe does the motor bolt to? Bottom or sides? If it is the side it does allow some leeway in motor placement since the wiring box will be on the top and not taking up space left to right so you will have more room for the pulley to be in the proper location. If the mounting point is on the bottom, then i would expect there to be an idler pulley or something to allow for belt tension adjustment.

 

[YYCHM]

You might want to check this thread out.....

Mill ways alignment problem

Hi, A buddy of mine -Marius - is working on a CNC mill conversion. He needed to enlarge the lead screw area to fit ball screws in. He gently used an angle grinder to open it up over a few days to minimize heat. However the front of the ways are now 0.004" wider than the rear. The casting moved...

canadianhobbymetalworkers.com

 

[Susquatch]

Ya, I'd be scared excrementless to cut that webbing. I would do anything and everything to avoid that.

My "opinion" for all 2 cents that is worth is that no manufacturer puts webbing in just for craps and giggles. The webbing is there for a reason. Might not ever know why but I'm not curious enough to cut it out to find out.

If you do decide to do it anyway, let us know what happened so, we can add it to that long list of things to never do again......

 

[Ian Moss]

I bought a tailstock from a large Japanese cnc lathe from a scrapyard to make a lever feed tailstock for my 14x60 Celtic Mondiale lathe. It was 13" long with a 3" diameter quill. The quill moved wonderfully until I bandswawed off the bottom of the casting to adapt it to my lathe. The quill jammed very solidly. Had to use a press to remove it and hand scrape the bore quite a bit to get it to move properly. I had believed that cast iron would not have residual stresses. I am wiser now. But, I would recommend a lever feed tailstock to anyone. Since I did the adaption, I have not used my standard tailstock for years.

 

[Redneck_Sophistication]

Ya, I'd be scared excrementless to cut that webbing. I would do anything and everything to avoid that.

My "opinion" for all 2 cents that is worth is that no manufacturer puts webbing in just for craps and giggles. The webbing is there for a reason. Might not ever know why but I'm not curious enough to cut it out to find out.

If you do decide to do it anyway, let us know what happened so, we can add it to that long list of things to never do again.....

I’ve already got such a LONG list already. (#1 Don’t stand in front of exploding things)

The base looks to be all 1/4” plate and not cast but seeing that it was cut in an arch I knew it was a bad idea.


Yes the motor is giant! I never knew all the frames numbers or what they meant, I always thought it was the bolt/mounting pattern.

I’m sourcing smaller ones now, the motor mounts to an secondary plate on the bottom of the base directly nothing for belt tensioning.

I figured I could mount to a piece of 1/2” plate and hinge it to the base for hight adjustment.

That’s crazy that something as small a tailstock would have that much internal stresses to bind up
Like that.

 

[6.5 Fan]

If your going to look for a different motor then maybe check on a 3phase and a VFD.

 

[RobinHood]

You could try and do a mock-up in cardboard to see what size (frame) of motor might fit in the available space.

You can do a calculation to determine the size of pulley you will need on the motor. Use the published spindle speeds and the gear ratios to determine the approximate input shaft rpm for each speed (they should all come to about the same number). The existing input shaft pulley size , rpm, and the motor speed (should be 1740 rpm) allow you to then determine the size of the motor pulley.

PA has a decent selection of double groove sheaves. The bores will be different - so can also be used to help determine the frame size of the motor.

All these little pieces of the puzzle might help you narrow down the motor you need to look for.

 

[Redneck_Sophistication]

I’m just looking at it now it’s an odd set up I wonder if I am missing something. Would older lathes ever use anything between the motor and belt drive?

The mounting plate is quite large and has tapped holes from previous mountings. There is holes with shim plates still sticking to the plate (very oily under there) on the FAR side of the web that’s in my way.

Looking at how far the belt needs to be over the motor couldn’t be much wider then 6” or very short only about 12” from the web to the pulley.

White chalk about Center of where the pulley should be

Looking at the speeds on the machine I’m now wondering if it originally had a two speed motor or two two speed gear box in the base???

Now that I think
About it The millwright I got it from last included a gear box actually I don’t know what for or what it’s from. It was a package deal (Bridgebort, lathe, air compressor, all gear drill press, etc was moving)

The beast of a motor I tried size15 work boot for scale

 

[RobinHood]

Can you please post some pictures of the headstock levers.

Can you confirm that the center lever has 6 gated positions, 3 on each side of the center neutral one.

Might be helpful to also pull the headstock cover to see the gear shifting mechanism - could give some clues as to how many speeds are available mechanically in the HS.

Your High to Low ratio is 1.25 to 1

Electric motors that are two speed usually come with high to low ratios of 2.0 to 1 or 1.5 to 1. (See this link to Baldor Motors: https://www.baldor.com/catalog#category=87). So it might not be a two speed electric motor but some sort of two speed servo shift gearbox with a single speed flange mounted motor driving it.

Do you think there was a mechanical or electric speed shift on the lathe at some point?

You have a picture of the gearbox and the specifications tag?

 

[Mcgyver]

The base looks to be all 1/4” plate and not cast but seeing that it was cut in an arch I knew it was a bad idea.

Reflecting on my first thoughts and post, I didn't think hard enough. My thought was that it was cast and part of the bed - which is rather daft as I have a couple of lathes with big casts bases which are of course separate from the bed. So, in messing around with the base, its not going to have the catastrophic effect on the bed as I first imagined. It could still twist the fabrication which could possibly induce some bed twist, and I'm still strongly in the camp of don't mess with it....but I'll downgrade my position to be a bit less alarmist as my thinking was erroneous (geez, good thing I caught was spell checker wanted to put there )