Removing gunge

I made a tiny stainless steel item on my lathe. I used Rocol RTD metal cutting liquid as the lubricant. No problems until the end when, as expected, parting off made the item very hot.

Unfortunately, I'd been rather lax and left a lot of swarf under the chuck, some of which was Delrin or Nylon etc. When the hot item fell into the swarf it melted the plastic, which had been discoloured with the Rocol, which then stuck onto the little item. The item has a 6BA screw thread and fine knurling and is proving very difficult to clean up.

Any ideas?

Hello Gary,

Try soaking in acetone and /or cellulose paint thinners. They may be aggressive enough, perhaps in combination, to soften the plastic

Regards Brian

I doubt you will have any luck with acetone if it is delrin as it is resistant to most common solvents. Nylon will dissolve very slowly in delrin. I would be tempted to try burning it off, then any char can be removed with a wire brush.

Adrian

You might try an acid like Phosphoric limescale cleaner, or a product such as Viakal. A test on an offcut of the metal would be a good idea first.

If burning any plastic as AdrianR mentioned, use extreme caution and do so outdoors with the wind taking away from you any fumes, preferably in an area with no people downwind for several km. I would recommend using a respirator mask rated for VOC's and particulates. The fumes from many plastics when burnt are extremely toxic , some are carcinogenic, and breathing them can cause illness or death depending on time of exposure. Please be careful!

The one thing not to do is polish it with wire wool. A stainless steel brush also might be preferable to a steel one.

I didn't have any acetone, but I did have some M.E.K. which is a very good solvent. It made no impression even after soaking for an hour. I then tried a small Dremel-type rotary stainless wire brush, which was far more encouraging. 10 mins of that, more or less did the job.

Thanks for the suggestions. Hopefully my lesson has been learned and in the future I'll clean up after a job.

Edited By Gary Wooding on 10/06/2020 14:55:41

Nylon is very good at solvent resistance, but poor with many acids. When I was in electroplating back in the 60's, everyone wore labcoats made from terelene. They started out white, but soon got dirty. The anode bags for the nickel plating bath were also terelene. Somebody in the management thought we would be smarter wearing nice blue nylon labcoats, so everyone had one. The record for the shortest life of one of the new coats was 3 hours before it fell to bits. My one lasted two days and before day three, we were all back in the old coats. We thought it was hilarious.