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An improved swarf shield for a mini-mill

Discussion in 'MINI-LATHE & MINI-MILL INFORMATION' started by hman, Apr 30, 2017.

  1. hman

    hman Active User H-M Supporter-Premium

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    Tempe. AZ -and- Corvallis, OR

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    Quite a while ago I mounted a DRO to my Harbor Freight 44991 (X2 mini-mill). I'd mounted the X axis scale on the back side of the table and used a piece of aluminum angle to cover it and protect it from swarf. Unfortunately, the "acccordion" swarf shield between the back of the saddle and the front of the column never did play nicely. I would get bunched up behind the saddle and restrict -Y tarvel. I finally figured out a way to improve the situation.

    The basic idea was to mount the front of swarf shield at the top rear of the aluminum angle, about 3/4" behind the rear edge of the table, and the back at the top of the column mount. With no part of the shield below table level, it would leave that area free for the DRO scale, as well as a stop rod I wanted to add to the X power feed. But how to allow for the X motion of the table? My solution was to devise a sliding mount for the front end of the shield.

    The sliding mount consists of three parts - a length of 1/2" OD copper tubing attached to the aluminum angle, a shorter length of 3/8" OD carbon fiber tubing (from a hobby shop), and a length of 1/8" rod. The first photo shows how the new swarf shield (a piece of .040" thick vinyl shower membrane) wraps around the rod and is captured in the carbon fiber tube. This tube slides freely inside the copper tube.


    I drilled and tapped the top of the column mount to hold the back end of the swarf shield.


    The next photo shows the setup I used to cut a 3/16" slot in the copper tubing.


    The tubing was held in a wooden nest mounted on the mill table. The lower edge of the rear vertical board extended a little below the base, to align against the back edge of the mill table. The front board captured the tubing. A small nail, visible at the right end, kept the tube from rotating.

    Because the slot had to be longer than available X travel, I milled as far as I could, then without moving Y, drilled another hole through the bottom of the tube, removed the nail, moved the tube over until the hole lined up with the original nail hole, replaced the nail, and milled some more. Rinse and repeat as necessary. The carbon fiber tube was slotted in a similar manner, using a 1/8" cutter.

    The next couple of photos show my initial proof-of-concept test.


    Seemed to work pretty well, allowing full motion of the table in both X and Y. The only downside I could see was that the clips I'd used to hold the copper tube in place got in the way a bit when I tried to brush away the accumulated swarf. I decided to mount the copper tube to the aluminum with epoxy instead. I first sandblasted a 1/2" wide area on top of the angle and on the lower part of the copper tube. These surfaces guaranteed excellent adhesion of the epoxy. The open ends of the tube also allowed making a somewhat wider swarf shield. Here's the result.


    I'm continuing to test the new system. So far, so good. I now have full (4.1") Y travel available!

    Though some swarf does get inside the copper tube from above, the open ends make it easy to sweep it out. The only downside I can see so far is that the tube will limit the size of work pieces I can mount directly to the table - I can only go about 3/4" beyond the rear edge. If necessary, I can slide out the swarf shield and raise the work piece with a couple thicknesses of 1/4" MDF.
    rdean, JimDawson, royesses and 2 others like this.

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