Dust cap modifications

[Ike]

That sounds great ibwiggin. I bought 20 bearings on line the other day for $1 each. If they are any good I will send you one. (I could send other spare parts as well.)

Ike, you now have to indicate which dust cap you are referring too!

Both caps, I know LHR bits are suppose to be calibrated with the chucks and I would think the motors Y and Z are chosen for the weight they carry? Just a thought I am not saying it won't handle the extra weight.

[bergerud]

Ike, if you think of the forces involved in controlling those cutting bits during carving and cutting, I think the extra weight of our bolt on stuff is negligible. Think of the power at which the carriage slams into that bit plate. Power to spare.

[DickB]

I've taken a break from this project as I need to get some other "real" projects done. I've switched back to my old dust collection system to regain my reference point so that I can compare performance. My initial take on first running the dust cap was that it does a better job, and I still believe that is the case. With the dust cap there is very little accumulation on the y rails an casting in that area. I get noticeable accumulation with my old system, and generally clean it with compressed air after every few projects.

I think that the dust cap does a better job of removing fine dust and preventing it from floating around in the machine. I think the rails, encoders, and gears are better protected with the dust cap.

I have not been able to contain all of the larger particles (chips) with the cap. To be sure, many chips are captured, but chips are still thrown around. The back side of a carving gets a lot, but this is relatively harmless, as the chips there are not affecting anything really. The far end of the machine, past the edge of the project board or sled, also gets a fair amount, but again that is relatively harmless. Some end up on the ledge on top of the casting, right under the clear cover. Some of this tends to vibrate off onto the board, and then get sucked up as the head passes over that spot. But the bottom line, and I can say this with more confidence now that I have reverted systems for a while, is that the dust cap at worst leaves no more chips than my old (current) system.

(My old system is a combination top mount and downdraft system. I may be able to get better performance by switching to top mount only, as I would have increased airflow in that area. I may try this.)

One drawback of the dust cap with the CarveTight is that there is very little clearance between the inside cap wall and the spindle screw. In fact, for testing the cap I had to remove the longer screw and washer recommended here: http://forum.carvewright.com/showthr...eTight-Spindle. I'm not sure if the cap can be made to work with this longer screw. One option might be to have the wedge part of the spindle machined with a bit more material or find a screw with a shorter head.

I'm not satisfied with my dust cap manifold on top. There are two issues. I currently have only a very short lip for the exit pipe to attach. I've attached it with an epoxy paste and it seems quite secure, but I would like to have more material there. And, the airflow makes a z-bend, which is not efficient and can be a place where larger, stringy shavings get caught. Both problems could be eliminated by moving the round exit pipe on top of the rectangular plenum, but this would mean that the slot in the machine's cover would need to be widened about a half inch, and that can't be done without addressing the cut motor safety switch.

[bergerud]

I think your comparison of your dust cap with the top mount is premature if you have not yet added the brush. Without the brush, quite a few of the larger chips shoot through the gap between the cap and the wood. These chips, because of their mass and velocity, escape the vacuum flow. The brush stops them and then the vacuum takes them away. The only chips which get away after the brush is added are ones which "bounce" though areas already carved. You can almost count them.

[ibewiggin]

So, my new parts shipped out on Wednesday. Where do I get the medium for carving my dust cap, and the other pieces? Also asked about the static earlier but had no response. Is static not an issue with this set up?

[Ike]

Ike, if you think of the forces involved in controlling those cutting bits during carving and cutting, I think the extra weight of our bolt on stuff is negligible. Think of the power at which the carriage slams into that bit plate. Power to spare.

I forgot I post the question! You mentioned the power to move the back plate and chuck to engage the bit plate. Well a little dust and the plate fails to engage and unless you clean and lube the pivot point it strains the Y motor. I know I don't keep trying to find the bit until I do clean and lube the bit plate. So I am concerned about the extra weight, again I am sure the motor can move the chuck with the cap. But the power is also needed for harder material, adding more weight would add more strain. Not to mention the motor is not a big motor compared to other CNC machines.

So many factors play in effect, dull bit, what material you are using, a clean lubed bit plate etc. I am not trying to a thorn in the side, but being a long time CW owner I can see issues with the extra weight! The ideal is awesome!

Ike

[bergerud]

ike: Just try and stop the carriage while it is moving. It has a lot of power. If you look closely at the bit plate, the reason it can resist the power of the carriage is because the carriage gets virtually no mechanical advantage and there is some scraping friction. What I meant was, look how hard it hits. Lots of power. Putting the weight on the z truck, on the other hand, would be a problem because of the high z acceleration. On the y - no problem - it does not accelerate much. Another way to look at it would be that the weight of the Dust Cap is only a small fraction of the weight of the whole carriage with the truck and the motor drive.

ibewiggin: I do not know what parts Dick is going to recommend making his cap from. If you go back to the end of the "To Carve the Dust Cap" thread, I have sort of a list. About static, I do not think there is much created compared with the high cfm systems. I live in a humid climate and so, for me it has not been a problem. I have thought, however, of finding anti-static hoses or hoses with a built in grounding wire.

[chkorte]

I love the concept but don't think I want to take my CW apart just to install it when what I have works so well and goes on and off in 1 sec. I certainly hope you get it to work.

[Ike]

ike: Just try and stop the carriage while it is moving. It has a lot of power. If you look closely at the bit plate, the reason it can resist the power of the carriage is because the carriage gets virtually no mechanical advantage and there is some scraping friction. What I meant was, look how hard it hits. Lots of power. Putting the weight on the z truck, on the other hand, would be a problem because of the high z acceleration. On the y - no problem - it does not accelerate much. Another way to look at it would be that the weight of the Dust Cap is only a small fraction of the weight of the whole carriage with the truck and the motor drive.

ibewiggin: I do not know what parts Dick is going to recommend making his cap from. If you go back to the end of the "To Carve the Dust Cap" thread, I have sort of a list. About static, I do not think there is much created compared with the high cfm systems. I live in a humid climate and so, for me it has not been a problem. I have thought, however, of finding anti-static hoses or hoses with a built in grounding wire.

Again I am not arguing the motor doesn't have enough power to do what it is intended to do! But a little dust on the rail and on the bit plate and the plate will not extend. Okay the Z truck moves the chuck up and down (vertically) The Y moves the Z plate left to right (horizontally) I am saying that out loud! Moving the dust cap up and down I would think would be okay. It is the the extra weight left to right under operating conditions while carving is what I wonder about.

I just wish an LHR engineer can say if the extra weight can be handled. I know they won't because any unauthorized add on will void the warranty. Not to mention be removed if sent in for repair. Floyd's DC is approved and when I can spare the funds I will get his! Again I love your ideal and I hope the best! I not against using non CW parts, I have a Rock on one of my CW, lol that I plan on switching to a Carve tight because the bits slip out of the Rock unless I make sure I really tighten it well!

Good luck with it I will keep up with the post and see how the dust cap works out!

Ike

[bergerud]

The up and down would be bad. If the cap had to move up and down, it would have to move with the high acceleration of the z truck. The reason for the flex cable is to make the z truck light so it can really accelerate up and down. The y movement, on the other hand is just slowly moving back and forth with virtually no acceleration. Carrying the cap is no big deal. In fact, the bit plate knock out would be even better with the cap on board. More momentum for the whack!

Anyway, it sounds like I am not convincing you. (It would be nice if the engineers at LHR would jump in once in a while. They do not seem to frequent the forum like they used to.)