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Discussion in 'CNC Mills/Routers' started by Paruk, Oct 1, 2014.
OX 1500 x 1000 mm
Prauk published a new build:
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Thanks for sharing the STL files. I like your idea of using the dual belt configuration. It would be helpful if you could post some pics or video on how to assemble the X/Y belts to give good alignment and sufficient tension on the belts.
It is not so difficult to do. Just take a double length of timing belt suitable for the axis you're working on and add about 200mm before you cut it. Fold the belt with the tooth to the inside and make sure that one end is about 120mm longer than the other. Place the double belt with the longer part on top into the top v-slot of the profile and secure the side that is folded with the A and B clip, having about 50mm going into the profile hole (see pictures in the build). Make sure the wheels are not too tight, push the double belt under the first 2 wheels, work the longer end over the pulley and slide the belt slowly further until the longer part can meet up with the lower belt just before it goes under the next set of wheels. Keep all as tight as possible. Roll the wheels now further backwards over the profile and pull the belt tight while you do this. Pull the belt as tight as you can while you fold it over the end of the profile and work it into the hole at the (now) other end. Take part B and, while you hold the belt firmly against the front of the profile to provide it from slipping back, push Part B into the hole to secure the belt. Now take the Part A and push it into the profile (as can be seen in the pictures) as far as you can. You might need a heavy piece of wood to hammer part A further in until it locks up the side and top of the belt completely. This system works on friction fitting and pull of the belt will only pull part A further onto the profile, locking it up even better.
After this you have to tighten the top belt by moving your stepper motor with pulley up (as can be seen in Mark's video). Not too tight because with this system the belt exerts its pulling force not further than just under the wheels. I suggest to NOT glue or stick the lower belt to the profile (as I did first and made things more difficult for me). The two belts together will be stiff enough to increase the accuracy of the axis by a factor ???.
Maybe I will do a video or so, but not in the very near future. I'm glad mine is just up and running and already have a lot of work for the Buffalo to do.
Are you the Martin on Planet CNC with the circle problem? Can you give some information about which stepper motors you're using? The advice of Andrej about setting the steps at 200 for X and Y is not correct if you use the Nema 23's from Openbuilds. The setting should be 26,66667 with the 3mm GT3 belts and 20 tooth pulleys, 1/8 micro stepping . If you do a calibration with a ruler you can get it a bit more precise than that.
Do you have any idea about the feed you're cutting with?
Thanks for the more elaborate explanation on how to mount the belt. I did a mock up yesterday and it worked!
I think it must be another Martin asking that wuestion on Planet CNC. As Im using the same stepper as the one you specifies I will try your setting.
Lets hope that "the other Martin" also follows this forum.
Good to hear it went OK, Martin. You used the A and B end caps I assume? Do me a favor and post some pictures of the installation (here or in your own build). Love to see how you did it.
The part A and B could not be use in my current configuration as Im using the end brackets from Roberts OX AL. They cover the end of the extrusion.
However, I think I found a good workaround using an adjustable tensioner at one end and fix the other end.
Yeah, an adjustable tensioner is very handy. I will try to work one out based upon the end cap. Did you already managed to test if the accuracy (as expected from the design) is superior to that of 1 belt? I found that my X is dead on. The Y has a little because there I switched to 1 belt because of the stepper driver problem I had before. When the new drivers arrive, I will get back to double belt.
BTW, make sure to have the upper belts not too tight, it needs a little bit to make sure the teeth will slide into the lower belt smoothly. So, just tight, no tension on the upper belt.
Robert's end brackets are good if made out of aluminium, I doubt if the thin MDF will give extra rigidity to the frame like that. Better is to use triangle forms (you know how strong triangles are, don't you?).
It's been a while. I have been busy with other stuff.
I seems like you have completed your build. I hope that it turned out to your full satisfaction.
Did you end using the dual (servobelt) belt configuration? - and if so did you update your design?
I still interested in this configuration and I have done some searching on the Bell-Everman home page. I found this video demonstrating replacement of the top belt.
From this it appears that they use no fastening of the top belt. It is only held down by end brackets. The lower belt is fixed to the rail using 3M VHB adhesive.
To me this seems to be the simplest way to do it (over tensioner, end caps etc) - agree?
PS The MDF I use is only for mock-up purpose. The plan is to mill the final parts in 6mm alu (or 8mm Granolite?)
Yes, I'm now using the double belts on all axis. On the Y I glued the 'rack' belt with super glue to the profile. That works very good. On the X I still have to fix the lower 'rack belt to the profile and will use this time the 3M VHB double sided tape (just found it somewhere, before it was not available here) to see how that goes. Accuracy doesn't seem to be an issue and skipping steps neither (also run now on 24V opposed to 12V before). I guess (since no real testing was done yet) repeatability should be 100% too with this setup.
I had no time to put the system to the real tests, yet. I've build a proper dedicated CNC router base table to give good stability and some work area around the Buffalo. It also lets me store the computer, have a movable monitor and lots of other stuff that involves CNC route ring. Also made a vacuum table on it, which works like a dream. With a 1200 Watt vacuum cleaner it holds the work rock solid in place. Also needed to move on with the building of my workshop and lots of other projects on the premises.
However, I added acrylic side plates along the Y axis rails to reduce the amount of dust and chips getting onto the rails and possibly causing trouble there. Next in line is a proper dust suction system to reduce the dust of mainly the MDF cutting(that is really bad stuff, man!). I found a very good solution, different from the dust shoe I'm using now and which is not too efficient, and need a bit of time with the overloaded brain to find the best way of attaching it to the router assembly.
I'll post some update pictures when I get the change in the next few days.
It's a good idea to put side shields on to prevent chips in the belt assembly. I would expect that it's even more relevant with the dual belt configuration. Chips going between the belts must be really bad - and difficult to remove.
I also made a dust shoe w cutting foam. It's not very good so I need to find a better solution.
I have played a little more with how best to make the dual belt configuration. I ended using thin 3M VHB tape to hold down the lower belt and it seems to work.
PS: Pics would be appreciated
PPS: I gathered my findings in this video: http://youtu.be/qXjLuLqFb-U
Thanks for the explanation on how to get the upper belt on easily.
A very useful and practical video.
Great video and explanation.
Very nice video Martin - clear and concise explanation for fitting the belts.
Yep, Martin! Excellent piece of work on the double belts. That is more or less exactly the way I did it, but found myself ready before even thinking about making a video of it. Couldn't get myself to take it all apart and do it again for the video. Thanks a lot!
Sorry for no pictures yet, the CNC room is a mess with all kinds of thing in it that don't belong there. We are in the middle of building a workshop and most of our energy and attention is going to get it done at the moment. Jumping from building walls, to making cabinets, to adjusting doors and painting them, to manage some builders that will come the next week to redo a part of the roof that was leaking due to some inferior flashing tape, to making a rocket stove for hot water in our field shower, to ..oh well a lot of stuff to do.
Will try to squeeze some time out of it to make a couple of quick pictures…..
Why are you "jumping off building walls"?
To make cabinets, you…you….
Suffering of a lack of motivation to take the trowel, brush or any other tool this morning I decided to make some pictures of the Buffalo in its present state.
This is the acrylic dust shield along the Y axis
This is the manifold for the vacuum hold down. There are 4 zones that can be activated individually or in combination with any of the others.
The little tool holder on the front, carrying the bits I use most.
I will post some more pictures later on.
Plus an overall view of the present setup. I have build a table to support the Buffalo while its doing its violent wood cutting.
The little blocks on the four corners are to keep the Buffalo in exact square, while still be able to remove it easily from the table by releasing some hold down screws.
To the left you can see some of the doors that are intended for the CNC room and another area, where the dust collector will come. In the back a picture that symbolizes the ending of my adventures on the seven seas (that boat is not mine, this I took on Isla Graciosa in the Canary Islands group) and at the right foreground the monitor of the computer system that is build inside the table together with the rest of the electronics. I use a bluetooth keyboard and mouse. Later on the computer will be outside of the CNC room to reduce the amount of dust coming into keyboard, mouse and monitor.
The CNC room will eventually be covered with a ceiling and have a central dust collecting system to remove dust from the air and the machine while cutting. Windows are double glass, also in the doors. The objective is to reduce sound to a minimum so I can work in the shop without getting nuts of the sound of routers and dust collectors.
Next CNC project will be a portable plasma cutter based upon the Ox design. For that I first have to build and finish the metal working room…...
Paul. That looks really really good my friend.
Thanks Gray! I hope to be able in the near future to get to some serious cutting with it. At the moment we have other priorities…… sigh.
I know exactly what you mean!!
Your setup looks really great, love the hold down setup.
So we had some guys replacing one half of the roof of my workshop (it was leaking due to some crappy flashing tape we bought here in Thailand). Guarantee job. This time we were positively surprised by the unexpected professionalism these guys showed. The repair is done almost perfect.
The workshop, with all its tools and CNC OX, really caught their attention and one of the workers offered to give me some wood he had laying around at his house. It turned out to be Burmese Padauk. The original plan was probably to make some small tables or seats out of it, since it was varnished and one side was more or less flattened. At first sight I didn't think much of it, it looked more like a partially worked at tree trunk slab.
So I decided to give it a try and clean it up. The pieces are too big to push through my 12" Makita thickness planer and too irregular to give it a try on my jointer (which would be too small anyway). Instead I came up with the cunning plan to use the Buffalo as a jointer/thickness planer. The holes in the vacuum table doubles up for bolts into threaded inserts to hold the workpiece.
Here are some pictures of the setup and before after cleaning up (not in chronological order!).
1. It worked very well, no problems at all with excellent results.
2. Next time I'll use the vacuum table as sanding vacuum table, sucking up most off the bloody dust!
Now I have to find some good use for this beautiful, very hard quality wood.
Don't make yourself think of a use. You know if you put it to one side, the ideal project will come along!
Perhaps a nice paying one?
Mind you. You can end up with an awful lot of nice timber waiting for a project.
Yep, guess you're right there. Got 2 nice logs of Teak, the nice stuff, not from a plantation but wild grown. Also for free, only had to cut them to length for transport. Did that by hand, never again! Waiting now for a chainsaw to arrive, to cut them into some nice slabs and let them season for a year or more. This way the timber is slowly starting to pile up, making me worry where to store it. ****!
I'm thinking about a project in which the use of a CNC machine, other wood working machines and good old fashioned handwork can be combined. Maybe I'll come up with something myself and sell the project after it is finished. Or go your suggested way and wait for somebody to commission a nice project with this wood.
Finally got around to design and print a new dust collection shoe for the Buffalo.
Wow! That one works excellent. Just did a test cut on MDF and not a particle of dust managed to escape this true SUCKER! Going to try tomorrow a slightly larger volume shoe to see if that makes any further difference, although, I'm satisfied about what I just saw. It works with a 1500 Watt shop vac.
Now that looks real interesting! Please keep us updated.