Got My First Lathe... Logan 1875 - With Restoration.

[Mr Mike]

Wow, that looks really, really good, Mike! Your lathe is going to be beautiful when you're done and you'll know every single nut and bolt of it. By the way, I like white, too, but my own lathe has a black bed and red carriage - this makes it go faster, you know.

So you have one of them sports lathe..? Is it fast and pretty..?

 

[mikey]

So you have one of them sports lathe..? Is it fast and pretty..?

Yeah, it's the Emco Super 11 CD - black and red and very pretty. Well, at least it is to me. Austrian-built like a Swiss watch, they run as good as they look.

 

[Glenn Brooks]

What do you mean "" Not a great recipe for doing a lathe bed, though... "" Did I do something that I should not have done...??

Well the scotch bright pads are abrasive by nature, which means scrubing the ways induces wear that reduces the accuracy of the ways, which in turn causes unwanted taper and variation in your dialed in depth of cut in when turning work. Most lathes of that era came out of the factory with something like .0005" or less of variation along the bed. Soooo, anything we do that contributes to wear, generally we want to avoid. The best approach is to use no abrasive pad whatsoever ever. Just wipe the ways down with Way Oil and a soft lint free rag. The way oil and rag will lift any foreign matter, including super fine metal shavings/dust. These show up as grey streaks on the rag. When you get no grey streaks on a clean part of the rag, you know the ways are clean. (This grey matter is a combination of minute metal scrapings scrubbed off the ways during contact with the cross slide, flash rust, dirt and dust floating in the air, and assorted small debris from making chips. basically sort of a powdered iron and steel slurry mixed with way oil. This stuff acts as an abrasive - grinding away at the accuracy of the flats and V surfaces of your ways as you move the cross slide back and forth. So getting rid of it now, AND each time you turn on your machine helps preserve the accuracy of your machine.)

Anyway, as you start rebuilding, here's a way to assess the condition of your ways. Sort of a first step...

Find (or borrow) a good straight edge and lay it atop your lathe bed. Turn off the lights in the shop and put a flashlight behind the straightedge. Look for any slivers of light between the straightedge and the ways. Heavily worn lathes will have measurable gap between the straight edge and the bed. Two of my lathes have really minimal wear - .003 to .005" -great for a hobbyist! One old, big iron machine, used as a production machine for the Canadian navy for 35 years, has as much as .018" gap, which causes noticable taper problems when I turn long work, such as axles.

So, All lathes have wear. It's unavoidable. So don't panic if you see a gap. Just stick a feeler gauge through the gap to find out how much wear you have and how much extent along the bed. You may be able to see a flash of blue, maybe green streak of light at the end of the gap. That is the beginning of any wear induced curvature in your ways. Finding that will help you determine what part of the lathe has seen wear- and help youmcompensate when leveling the lathe after you have it reassembled. BTW, wear is usually the worse right around the front of the chuck on the Forward left hand side of the bed -closest to where the operator normally stands.

Be interterested to know what you find out.

Glenn

 

[Mr Mike]

Well the scotch bright pads are abrasive by nature, which means scrubing the ways induces wear that reduces the accuracy of the ways, which in turn causes unwanted taper and variation in your dialed in depth of cut in when turning work. Most lathes of that era came out of the factory with something like .0005" or less of variation along the bed. Soooo, anything we do that contributes to wear, generally we want to avoid. The best approach is to use no abrasive pad whatsoever ever. Just wipe the ways down with Way Oil and a soft lint free rag. The way oil and rag will lift any foreign matter, including super fine metal shavings/dust. These show up as grey streaks on the rag. When you get no grey streaks on a clean part of the rag, you know the ways are clean. (This grey matter is a combination of minute metal scrapings scrubbed off the ways during contact with the cross slide, flash rust, dirt and dust floating in the air, and assorted small debris from making chips. basically sort of a powdered iron and steel slurry mixed with way oil. This stuff acts as an abrasive - grinding away at the accuracy of the flats and V surfaces of your ways as you move the cross slide back and forth. So getting rid of it now, AND each time you turn on your machine helps preserve the accuracy of your machine.)

Anyway, as you start rebuilding, here's a way to assess the condition of your ways. Sort of a first step...

Find (or borrow) a good straight edge and lay it atop your lathe bed. Turn off the lights in the shop and put a flashlight behind the straightedge. Look for any slivers of light between the straightedge and the ways. Heavily worn lathes will have measurable gap between the straight edge and the bed. Two of my lathes have really minimal wear - .003 to .005" -great for a hobbyist! One old, big iron machine, used as a production machine for the Canadian navy for 35 years, has as much as .018" gap, which causes noticable taper problems when I turn long work, such as axles.

So, All lathes have wear. It's unavoidable. So don't panic if you see a gap. Just stick a feeler gauge through the gap to find out how much wear you have and how much extent along the bed. You may be able to see a flash of blue, maybe green streak of light at the end of the gap. That is the beginning of any wear induced curvature in your ways. Finding that will help you determine what part of the lathe has seen wear- and help youmcompensate when leveling the lathe after you have it reassembled. BTW, wear is usually the worse right around the front of the chuck on the Forward left hand side of the bed -closest to where the operator normally stands.

Be interterested to know what you find out.

Glenn

Thanks you sir for sharing your knowledge on this subject.. I'm brand spanking new to the lathe world - where might I get a 48" straight edge that is dead on straight.? And how does one check to make sure the straight edge is straight before its used as a true gauge.

 

[wa5cab]

Assuming that the straight edge is a good one and not off of the $2.99 bargain table at the auto parts store, set it on the bed with the lights out and the flashlight behind and see what you get. Then turn it over and check again. If it isn't straight, the two sight pictures won't be the same.

 

[Mr Mike]

Yeah, it's the Emco Super 11 CD - black and red and very pretty. Well, at least it is to me. Austrian-built like a Swiss watch, they run as good as they look.

I looked up the lathe its White, Black and Red.. Nice little sports car you have there.! Lots of buttons - I like Buttons.

 

[Mr Mike]

Assuming that the straight edge is a good one and not off of the $2.99 bargain table at the auto parts store, set it on the bed with the lights out and the flashlight behind and see what you get. Then turn it over and check again. If it isn't straight, the two sight pictures won't be the same.

Hello my good man...
The big question is, don't you first have to verify that the strait edge is strait.. Is there a preferred method for doing that..

I don't think it would be wise to just assume a strait edge is strait.. Unless I'm missing something here, I have had many instances where the tool I was using as a gauge to test another device was out of calibration. Just recently while doing this project I had to use a digital caliper to determine when I had cut my Rebar bolts to exactly .24 inch. My super accurate caliper on occasion would add .01 which cause me to pull it from the chuck after cutting off to much...

Thanks Mike.

 

[Bob Korves]

What do you mean "" Not a great recipe for doing a lathe bed, though... "" Did I do something that I should not have done...??

Evaporust is $20+ per gallon. Though it works really well, buying enough to do a lathe bed is a large investment, at least for a cheapskate like me. I think electrolysis is the way to go with bigger chunks of metal that need to look really nice when done.

 

[Bob Korves]

Well the scotch bright pads are abrasive by nature, which means scrubing the ways induces wear that reduces the accuracy of the ways, which in turn causes unwanted taper and variation in your dialed in depth of cut in when turning work.

Yes, the light gray super fine Scotchbrite pads are abrasive. but barely so. You would need to scrub for a LONG time to remove enough metal to measure. Using one helps to remove the stains and blend in the surface finish of the ways, so it looks better. It also feels much smoother and less gritty afterwards, so some of what it removes probably needs to be gone. The down side is that it is an abrasive, so any left on the bed after polishing will keep working on and on, so it must be really well removed after using it. I only think of this sort of approach, of using any abrasive on the lathe bed, as a final polish for a restoration project, and only using it by hand, not power. I would certainly not use it for ongoing maintenance or regular cleaning use.

 

[Glenn Brooks]

Hello my good man...
The big question is, don't you first have to verify that the strait edge is strait.. Is there a preferred method for doing that..
.

Is a straight edge, straight? Ahh, now we jump into the deep and the arcane! Depends on how level is the surface you use to measure the edge. And the precision of the instrument you measure the surface. Metrology is a subject approaching philosophy and way beyound my meager knowledge. Actually there is a section on this forum that has several interesting discussions about this.

However there are some practical methods. Robert,above, posted a very good method to verify straightness. Usually you do this three times, with three different locations on the same reference surface, then average the three. You could also use a granite surface plate. Even a large square of plate glass will do. Precision straight edges are large, heavy, reinforced and very expensive instruments - in the realm of thousands of dollars. Delivered with an inspection certificate guareeteeing variation in the edge in the area of tenths or less - ten thousands of an inch. One must hang these vertically to insure the metal doesn't take a set and throw off the edge. So not generally available at a decent price.

Personally for a quick check i have used my aluminium carpenters rule - which I have found to be surprisingly 'straight'. Stainless 18" drafting rulers are often pretty good. You can measure deviation of what ever straightedges you might have around the shop, with feeler gauges, mark location of the variance on the device with a marking pen and subtract from your way measurements - gives you a reasonable assessment in thousands. For me, good enuf. I don't worrry much about nano measurements.

As to where to find a decent straight edge. you could check eBay. I've seen a lot of 'surplus' high quality metrology instruments coming out of Russian - old soviet block countries - for cheap. Apparently old time socialist party machinists turn out to be pretty good entrepreneurs!

Glenn