[freak_brain]

All,

I have looked at a lot of pictures on here of different peoples machines. So far I have seen no covers over the rack and pinions, linear slides or any other precision movement parts. Doesn't spatter fly when piercing the material? Or is this not even a consideration? Is taking the time to protect these surfaces not time well spent?

Thanks
Allen

[cbass]

Hey Allen,

I think there are a few reasons why many people don't bother. For one, the stuff that is being cut isn't very abbrasive (i.e. plastic and wood). Perhaps another reason is that covers need to be engineered into the mechanics ahead of time in order to be effective. Maybe cost is another factor.

I'll be cutting ceramics which are very abbrasive, so I'll be implementing covers for all axis and ballscrews. Unfortunately I've already ordered my machine, so I'll have to engineer them into the system. I've already lost many hours of sleep thinking about how to do this. My y axis cover will envelop the entire gantry (slides and screws). Because of my machine's design (k2cnc kt-3925) the X axis will require a lot more work. I'm actually thinking of using a square sectioned bellows cut in half. The edges of the bellows will be emerged in a chanell of oil on either side, allowing free movement while isolating dust from reaching the slides and screw below. I'll post images when I draw this up. I'm not sure how to tackle the Z axis yet.

If you're interested in sourcing these out, search MSC for Gortite covers.

Carlo

[traveler]

Because you are asking these questions in the plasma, laser, waterjet section of posts, I assume you are (never a real good thing, to assume) intrested in one of these methods. Because waterjet is done under water, it dosen't generate airborne abrasive. Laser is at this time too expensive for me to play with, so I cannot comment of it. As I see it the most likely situation you are facing is with plasma cutting. You are right on target to be concerned with the airborn trash with plasma cutting. The danger is both in your personal health and the potential damage to your machine. Plasma cutting just puts a LOT of trash in the air. My solution may not fill everyones needs, but the way I handled it was to mount the rack on the "X" axis tooth down, so the airborne dust would not accumulate in it. The "Y" axis design did not allow the tooth down method so I mounted it tooth vertical. Neither mounting methods have given me a problem with trash accumulation. For personal health, I have put a skirt around my table (cuts 48" X 96") and installed a huge fan to pull the smoke and grit down and out. This goes a long way in keeping the dust from accumulating in the racks or my lungs.
I think it may be proper to look at the expected life span of what we are building when we design these machines, as well as the repair- replacement cost of parts as opposed what it will cost to design a "forever" machine. My machine has undergone several changes and upgrades and if I were to have been overly worried about wear prevention I think I may not have been so quick to upgrade the drive system because of cost. I see my machine as a work in progress at all times and if I ever feel that I have created the perfect design and will never want to change it, I will turn my attention to covers at that time.

[doug6949]

Traveler;

Even under ideal conditions, abrasive waterjet systems have a tendency to blow abrasive around the shop. Mixing chambers clog, operators spill garnet, some parts must be cut above water. Piercing operations direct the abrasive stream upward until the hole punches through. The AWJ shops I've been in (including the labs at Flow) were dusted with garnet.

Doug

[doug6949]

The cost of bellows covers is probably the main reason why they are rarely included in cost-concious designs. The best alternative I've seen is the window shade approach used by Les Watts on his router.

Les used coated fabric (available from MSC) and wind-up rolls at each end. The system is effective and cost was a fraction of what would have been spent on bellows.

Pressurizing the 'clean' areas with a muffin fan helps to keep dust out. You can buy a cleanable HEPA filter for a shopvac for about $30 to filter the incoming air.

I designed a gantry to use 10 inch wide .015 spring steel for the curtain. Instead of rolling it up at each end, the curtain rolls around the ends of the gantry and along the back side. Thus, one continuous piece encloses the space. The biggest problem with this idea is that the end rollers add more than a foot to the length of the gantry.

Doug

[traveler]

Doug, thanks for the correction. The only waterjet I have seen in operation was under water and I didn't see evidence of grit in the area. I admit that the outfit that owned this machine kept a super clean shop had it in a separate room and I was not looking for the dirt. Anyway I now stand corrected.

[freak_brain]

All,

Thanks for the informative replies.

I was kind of thinking about using, as strange as it may sound, tape measures. The extend and retract like one needs. Modifications would be needed but it's a start. Food for thought.....any other ideas?


Thanks All
Allen

[coherent]

I just welded a piece of 3 in wide 1/16 in steel under my plasma "slat" holder table. The plate sits right above, and the length of the X ball screw and although I get a lot of splatter on other frame parts, the screw is clean and have had no problems.
-Marc