Inexpensive chip shield for my 1340GT

[rherrell]

I got tired of dodging hot chips so I decided to make myself a chip shield. I looked at the Flexbar but when I saw the price I decided to make my own.

It's a 1/8" piece of plex about 8"x15" with some cut outs and a 45 degree bend on one side. I wanted it removable so it's mounted with a magnet in the 1" alum. base. I used a piece of 1/2" drill rod for the upright support. REAL simple to make and it works great!

 

[mksj]

Rick et al,
Plexiglass/acrylic sheet can be very dangerous when used as a protective shield, as it shatters very easily. It is really scary stuff, a few times when I have used it, it quickly formed stress cracks around bolt holes and shatters into pieces with minimal impact. I would recommend using polycarbonate sheet (Lexan), which is much more durable/impact resistant and will not crack or shatter. It is readily available at hardware stores.

 

[rherrell]

Good point Mark, if it ever breaks I'll get some Lexan. I never take real heavy cuts so my chips are small, but if you remember I have to sit when I use the lathe so it keeps the hot chips out of my lap and off my forearms. Plus, it's about 6" away from the chuck so it doesn't get hit very hard.
I'll keep an eye on the bolt holes, if I see it start to crack I'll change it.

 

[Clock work]

Nicely implemented. I use an on/off magnet for mine but that cost more than is necessary.

 

[RJSakowski]

Polycarbonate (Lexan) will form stress cracks just like acrylic does on machined surfaces. In addition, various solvents, including cutting oils and lubricants will expand the cracks. I made a Lexan lens for an LED light on my Tormach CNC and within a few weeks, stress cracks were visible. After a few months, the cracks had expanded across the entire lens, rendering it useless. I replaced it with "clear" PVC from McMaster Carr. It has been in service for several years now with noi sign of deterioration. Unfortunately, the clear PVC is only translucent and wouldn't work as a window.

I suspect that micro-cracks and/or fissures are formed during the machining process which form the nucleus for a larger crack to follow. Treating the machined surfaces with solvent type glue may reduce the tendency to crack. Providing a an elastic interface between fasteners and the polycarbonate will also help. A rubber washer backed by a fender washer, for example.

 

[mksj]

RJ,
I am a bit surprised as to the problems you experienced with the polycarbonate (PC). I have made shields, and also when I built boats we would routinely use if for deck hatch covers and covers for instrumentation. In all those years I never saw a stress crack at a screw hole or for that matter it break with an impact, even dropping winch handles on hatches. It is commonly used for bullet proof barriers. It may be that there are different grades, or there may be some aging effects, but using it in deck hatches I had never saw a failure in many years. CD/DVD discs are usually made out of PC, and are for the most part are unbreakable even with folding them over.

 

[RJSakowski]

I was surpised myself. Iwas aware of solvents like acetone attacking PC but didn't expect a water based coolant to do so. In my case, I believe that the cracks propagated from contact with my water soluble coolant but they clearly originated at the drilled holes and/or counterbores. I had machined the lens from 1/2" thick polycarbonate. but the machined surfaces were not exposed to coolant except at the edges and the counterbores. I have noticed that both polycarbonate and acrylic are less resistant to solvents in contact with machined surfaces.