I’ve been plugging away at my own attempt at an improved Z-Axis for awhile now and I think I have a version of it which I’m happy with. I figure I’d show this to all of you that are much smarter than me (so, everyone on this forum) in case there are oversights I’ve made. That way, we can catch them before I try putting this all together and go “wait a minute…”
Here’s the current iteration:
I highly recommend looking at this link to the model (available on the Fusion360 cloud) to get a better idea of how everything fits together:
I’m planning on using 3/4" baltic birch for most of the components. Pretty much everything is tab and slotted together to locate my parts accurately. I plan of glue-and-screwing the parts together. You can actually see my pilot holes in the model. I will be transferring my 1/4" HDPE pad from my current test sled to this “final” sled.
The dust hood components I’m planning on 3D printing. The main part of the hood will use most of my print bed. If I have too much trouble with the printer, I’m thinking I might also be able to machine it from 3/4" baltic birch or maybe even acrylic. There is also a “window” that I will make from clear acrylic.
The Z-Axis lead screw and rails are from the kit @StephenMcG used for his sled. For the time being I’m still planning on using the Rigid R2900 (almost the same one as the recommended one) I’ve been using so far. I may look into equipping this sled with a more powerful CNC spindle down the road.
The only thing not modeled are the weights. Even though I went through all the effort of modeling this, I haven’t used Fusion’s materials to estimate the weight of all the plywood. I think I’ll just wait until I have it assembled, then add my steel weights to the sled until it reaches my target weight, ~30-40 lbs.
I am thinking I might make a proper final version from machined aluminum somewhere down the line (maybe when I get a new spindle?)
Community Garden link:
Woah! I like it a lot…especially the way you did the dust collection. Can’t wait to see the final version
I love it. Great work. Keep on it.
Thanks @bar and @Bee! If there’s no glaring issues I may just get started on this this weekend
I am planning a similar approach for my sled, but I plan to use aluminum plates and brackets. Unfortunately, my Maslow progress has ground to a halt while I work on several house projects…
Great model! @MeticulousMaynard Any scope to include the ring system on the same style of sled?
Great minds think alike! I think our machines probably are going to be pretty similar
Sorry to hear about the progress. Keeping the house in order is very important. I’ll be moving into my own house this spring and I’m imagining I’ll be spending most of my free time getting it ready.
Yes, actually! Although only by chance, the footprint is very similar between the linkage and rings.
I modeled up the ring when I saw @bar’s template for it in the ring development thread:
I’m not sure if the design has changed that much, but it looks like the ring should work quite well. There’s a lot of clearance on the inside so the bearing carriages should be able to move around without hitting anything.
I have the kitchen for my new home to draw tonight, but if I have time I will try to get the parts nested as well. When I do, stl’s/dxf’s/svg’s for all! (I believe Fusion can output svg)
What is the distance motor to lead screw? center/center in mm
As it is in my drawings, it’s 70mm. In real life, I’m going to slide the
motor to the side a little to help tension the belt, so it will probably be
a little more than that.
I’m sure you’re aware, but be mindful that toothed belts don’t require a whole lot of tension to be happy.
Yeah, that’s the nice thing about timing belts. I’m still thinking I might have to tension it a little, mostly because I’m buying an off-the-shelf belt instead of one sized exactly for this use. We’ll see how much tension it actually needs when I put it together.
Do you need to invert the direction on the z motor? how?
Yes, using a timing belt in this fashion means that the Z-motor will need to be inverted. In Ground Control, you can set a negative Z-Axis pitch and it will reverse it’s direction.
I’ve got everything nested and .nc files made. I’ve used Convertio to make an svg file from the dxf. I checked the scale in MakerCAM and it looks off, but I’m not sure how to check dimensions so I can’t scale it correctly. The outer diameter of the sled should be exactly 500mm.
This zip file has dxf, svg, and the nc files I’ve made:
Prototype_Sled_Parts.zip (87.2 KB)
There are four tool changes for the sled! I tried to make it as easy as possible but the spindle clamps need an 1/8" bit for the relief cut. When I post with multiple tools, I make couple different versions of the program. I make a single-tool program for each of the different tools, that way I can run each one on its own. I’ll do my tool changes between programs. I also make a program which has everything in it, in case I feel gutsy and want to run everything at once. This time around I’m going to try the “all” program
Once these programs are proven and I have assembled everything successfully, I’ll post the contents of zip file to the Community Garden along with building instructions.
On a side note, I noticed as soon as I laid everything out that I didn’t dogbone my tabs. I was able to fix it quite easily with the dogbone plug in. If you’re not familiar with it and you model in Fusion, this is a really useful tool! It’s much, much faster than drawing all of them manually. I highly recommend checking it out:
Where are you sourcing the motor bracket, pulleys and belt? Links?
The motor bracket is the one that comes with the Maslow Z-Axis kit. It’s only 1 of them, so it might look a little weird at first.
As for the belt, it’s a 10mm wide T5 timing belt. The drawing uses a 225mm long belt. The pulleys are 15 tooth, 28mm in diameter from the model. This pulley has a 6mm bore, which will mate with the motor shaft well. The pulley on the lead screw will need to be drilled/reamed out to 8mm.
One of the things that I want to play with the tooth count on the pulleys. I can significantly increase the axis travel speed over the Rigid base. According to my calculations, I may want to do a 0.5 ratio to give me significantly more feed speed. The Rigid base manages just under 40mm/min. With a 0.5, the axis would travel at 120mm/min. The largest pulley that McMaster stocks that still has a 6mm bore for the motor shaft has 26 teeth. That would give me a 0.385 ratio, which would result in 156mm/min of travel.
As a heads up, different gear ratios will (most likely) need different length belts.
Of course, the logical thing to do would be to get a motor that has less reduction in the gearbox. Then I could just do a 1:1 ratio at the belts. This probably will be the long-term solution to the problem.
225mm x 10mm T5 Timing belt
15 tooth timing belt pulley
10 tooth - For lead screw
20 tooth - For motor shaft
26 tooth - For motor shaft
EDIT: If you want to look at the math behind the gear ratios, here’s the spreadsheet I used as my calculator:
Gear_Ratio_Calc.xlsx (12.5 KB)
If I read the drawings right, the 300mm kit would work fine. Is that correct?
Yes. As it is drawn, the linear rails are 300mm. The lead screw might pop up a little more than I have drawn, but it won’t interfere with anything.
For anyone who might still be following this thread, I’ve made a couple of updates. I’ve added a link to the first post that link to the community garden, which includes all the files you will need to build it.
I hope to build this very soon, all my Maslowing plans got postponed due to my recent move. I should be getting back to the shop in a couple of weeks, and I will post more updates as they arise!