In the spirit of trying to share negative results, I thought I‘d share a project that didn’t work. My goal was to improve dust collection by making the dust boot move independently of the spindle. The thought was that it would be able to always be the right length, then raise itself when it was time for a tool change.
So I made a boot that had a small stepper motor in it to raise and lower the bristles. And long story short, it doesn’t work well at all. The boot is simply too big, if the stock being cut isn’t big and flat there are just too many places for air to come in. (The attached photo doesn’t show TPU bellows I printed to get rid of the big hole around the spindle, but it didn’t help much.)
I’m curious what the collective wisdom is around dust boots. In particular I was pondering if it would be better to have a smaller circumference on the dust skirt, if that mean having a restriction in the airflow to get it from the 4 in hose to closer to the spindle.
I’m sort of pondering a few possibilities.
Remake it with the ballscrew on the left of the spindle, and just a linear rod for stability on the right. This would let me get the hose a little closer to the spindle.
Make something a little closer to the style of the avid boot, but then work out a way to dock / undock the boot magnetically when it was time to do a tool change.
Just go back to the boot I was using in the past.
I hope someone was able to learn from my mistakes… I’ll let you know if anything actually works well.
ahh, the adventures in dust boot design. I know thee well.
I have been designing my setup for the better part of 2 years now. I originally based it off of Pete Squared’s design he used to sell (that I purchased, but he has since removed).
I wanted to have something low profile that doesn’t have to get out of the way for tool changing on an eventual ATC, so I spent many hours calculating cross-sectional areas for this design:
This is mk16. I am currently prototyping the boot end in PETG. But the basic idea is to move the full 4” diameter, farther away from the tool, giving more clearance for fixtures and tool changes. The boot is supported by 4 steel shafts I have from a 3d printer upgrade. This boot carriage is mounted to the z-axis mounting plate, so the z-axis doesn’t have to carry the weight of the boot.
The iso 30 tool sticks out completely from the bottom, and the brushes are held on magnetically. So if something were to crash, it would just be a simple brush ring. I also have 3 heights of brushes for longer tools. The idea would be that the tool fork can move the brush bristles out of the way very easily, so lateral tool fork entry is not a problem.
My struggle right now is how to set the height. I could use a simple clamp on a shaft to set it at one height for the entire job, but Marius Hornberger put that auto-height idea into my head x_x. Right now, I am planning on it being spring loaded, so it rides the z-axis being pushed by the spindle up and down. But I dont really love that idea.
I am curious about where you head next. I would love to motorize / solenoid it, but I need to figure out how to do that on a servo EX system >_<
I love the effort here. Anything worth doing is worth overdoing
It seems the biggest problem of leakage is due to the big oval shape of the brush. I had a design like that for a long time, and when the hose side goes off the edge of the workpiece or you are not down on the workpiece, it just doesn’t pick up well. Thats what I like about AVID’s current design (and many other dust boots are this way now too) where the brush itself is a circle only about 6” diameter. Even when the bristles aren’t touching down the vacuum collects debris very well on smaller diameter bits (up to 1/2”).
Thanks for the thoughts. I am tempted to go the small circle route. For my most common tools I have gotten tool holders in a few different lengths so that I can make the holder + tool length close to constant for purposes of the dust boot being in the right place.
Any thought on the right diameter for the dust boot circle? I imagine the smaller the better, but too small and you risk the bristles getting pushed into bit.
Another thing I’m pondering is if I want the boot to be dockable for tool changes, or if I want to switch to the cup style tool holders. I’m thinking if I make a some TPU fingers to fit into the groove at the top of the holder I might be able to handle some of the loading / unloading problems I was worried about with a completely solid holder.
I’ll update this board if I get results from that.
This looks like a really nice design. Do you think it would work with a winerack style tool holder? I was originally thinking I needed max clearance to allow for that, but now I’m not sure if that is the tail wagging the dog. Maybe a different style tool holder is better than a giant contraption on the spindle.
Perhaps I would have more luck with a dockable design and couple of different bristle lengths. Maybe they don’t need to be that adjustable.
I’m glad to hear I’m not the only one tinkering with this idea on and off.
I think the diameter of AVID’s (6”) is good. With the longest brush length and my 2.5” slab slayer bit the bristles stay out of the way of the tool.
I think with this size, you would have room to use a fork style holder for most bits as long as the fork was held by a pedistal so that there was space between the forks for the dust boot, and as long as you have some control of the horizontal travel of the in and out movement to the fork to keep it somewhat minimized.
I’ve made a few dust boots for different machines with different tool change strategies. My current setup is for very large diameter tools 3”-3.5” and very thick material 1.5”-2.25”. Also, I think it’s the funniest dust boot I’ve ever made. We named him Gus. The guys in the shop put on the eyes. I then couldn’t help myself but to give him a nose. I know this isn’t that helpful, but it’s funny anyway.
Before starting a new small circular dust boot I decided to make sure that I could make pocket style tool stations work. And after a bit of experimentation I think I can.
The trick that seems to have worked was printing a ring out of TPU to catch the tool and hold it in a consistent place, but with some give.
The final recipe that worked for me was to print the above in a 90A hardness TPU with 1 wall, and gyroid infill.
What didn’t work was trying to make a design with “fingers” in the photo below. I spent a bunch of time designing the “I-Beam” style interlocking between the TPU and the petg, but I couldn’t get the stiffness of the fingers just right to hold it in place firmly, but still get bent out of the way when the tool was being returned.
This design could be improved by mounting it below the spoilboard to increase pocket density. But I think it works well enough that it is time to make a boot that can use it.
