Should I paint the inside of my lathe apron or not?

The apron in the photos is from a 1962 Saimp 14 X 40 (Italian) lathe. I had some annoying oil leaks so decided to try and fix them which required a complete tear down (major pain in the ass). It appears the factory painted the inside of the apron with some kind of paint that actually sticks to a magnet. It seems pretty strange but sure enough I can remove loose paint with a magnet, it's not a very strong attraction mind you but strong enough to hold the paint flakes on the magnet during extraction.

When you guys rebuild machinery, lathes in particular do you paint the inside of such things as the apron? If so what type of paint do you use? Thanks in advance

Ron

I don't know enough to suggest the proper paint, but I would think YES, paint it.
After cleaning it out, then cleaning it again a good coat of paint will help trap any bits of flaking from the old paint in there.

I would imagine a good two part epoxy paint would be the ticket.

There always seems to be a crevice somewhere in cast iron with a bit of casting sand attached to it, painting with epoxy would help prevent it coming loose and seal any possible porosity. You'll have to do a fair bit of degreasing and warming /drying with a hot air gun first

Back another lifetime ago I worked at a Harley Davidson dealership as a mechanic. It was standard practice to paint the inside of cases with rustoleum red oxide primer to seal them. I am sure there are better products out there but I disassembled many a high mile motor that still had the paint all in one piece. That is inside an air cooled engine so it has always been good enough for me.

When we repaired our machine the pieces went to caustic vat and then steam cleaned. Painted as soon as it dried. With Gliptal., now the have a two part mix.

bridgedog said:

Back another lifetime ago I worked at a Harley Davidson dealership as a mechanic. It was standard practice to paint the inside of cases with rustoleum red oxide primer to seal them. I am sure there are better products out there but I disassembled many a high mile motor that still had the paint all in one piece. That is inside an air cooled engine so it has always been good enough for me.

Click to expand...

That was Glyptol. I used to do the insides of motor cases and trans cases with it, years back. Works well to seal the porosity issues of that, and the earlier eras.

Glyptal Red Enamel


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I will third the suggestion to use Glyptol

I would suggest you pull out the lube pipes, bearings, shafts, everything and take it over to an engine rebuilder and have them wash it in their hot water rotary wash tank. Might cost you $10.00. Painting a cast iron casting soaked with oil in my opinion is looking for trouble. I have seen where a competitor painted inside a tank and the paint peeled off and plugged the lube system. I would not paint it if you don't have it washed properly. Those rotary washers wash car engines, inside heads and they paint them. I would also go to Sherman & Williams and buy a quart of what they recommend. I used to use Alkyd oil based paint after wiping everything down with a good grade of lacquer thinner. You may go to tractor supply and get tractor paint.

Rich

Thanks to all for your suggestions and cleaning tips. I've used Glyptal in the past to coat the inside of electric motors and generators but never knew it was also used to coat the inside of engines.

The plan is to remove the lubrication lines and clean the apron inside and out. Then coat the inside with Glyptal unless something better is found.

Thanks again.

Ron

Finally the lathe apron is done and what a major pain in the ass it was. Mainly because it is such a narrow gear box and everything is hard to access. But the main problem was the paint I used to coat the inside. I tried to find a pint or even a quart of glyptol but could only find it in gallon size cans at $109 per gallon. So based on a suggestion from a HSM member I looked into POR 15 coatings. I called the factory and talked with an application engineer to get some answers. I must say this guy was quite knowledgeable and answered my questions completely. He even cautioned me to take care and not get the paint where I didn't want it.

I took great care in cleaning and preparing for paint and was extra careful when brushing on the POR 15 but it's tough when painting in such tight quarters. So I did get some paint in precision bores, threaded holes and on machine surfaces. Some of the bores for shafts are blind and required creative tooling to clean them out. Threaded holes inside the gear box were particularly hard to clean out as were the blind bores.

POR 15 coating is extremely tough stuff but I would never use it in an apron again, it was just to hard to get the stuff off surfaces you didn't want it on. But it would be great in very demanding applications.

Here's some photos of the finished product. POR 15 comes in black, white, silver, gray and clear, I used silver.

Looks nice!
Post #7 contains a link for Glyptal in quarts.


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Stradbash said:

Looks nice!
Post #7 contains a link for Glyptal in quarts.

Click to expand...

Yep. What he said. You're a better man than I. I would never have done that. Stubborn. Like Bull.

Also, in the future a little more homework might help you save some effort. LINKY The 225ML bottle is one choice, and the other link provided above is a Quart that is available many places. I know some motor rebuilders that use it every day so have to believe that it is commonly available.

But you got the job done and that's all that matters.

Yes, Glyptol was my first choice but try as I might I couldn't find it locally anywhere except a gallon can at a distributor in Anchorage. I checked several automotive machine shops, two electric motor repair shops, all the paint stores and about a dozen other places with no luck. Most had never heard of Glyptol and both electric motor repair shops knew what it was but started using using a different product years ago.

I was able to buy POR 15 locally in a 1/2 pint can and only used about 1/3 of it for the apron gear box and the underside of the carriage. I soaked the apron gear box in sodium hydroxide for 24 hours then rinsed it and the container then did another 24 hour soak followed with a pressure washing and then a metal prep and conditioner was painted on and let dry before applying the POR 15. I must have done something right because the POR 15 was a real bastard to get off. I'll use it again but never in a small hard to access narrow gear box or anything with limited access.

FYI, I checked with a machine shop to see how much they would charge to dip my apron gear box in their hot tank to clean it, $100. So I paid $20 for some sodium hydroxide and used a 15 gallon tupperware tub with a lid as my tank.

Ron

Oh..., Anchorage. Understood. I just sent a stuffed animal there and it cost $55.00 to do so.



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I wonder if the old paint that stuck to a magnet was red oxide primer. It has iron oxide as filler and to add the red color.
Bill D.
Pictures are gone thanks to ?