Have you thought about just using one belt and one motor and drive, I use two motors but quite a few on here use one as it is easier to home and stops the problem of racking etc. Just a thought!
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Have you thought about just using one belt and one motor and drive, I use two motors but quite a few on here use one as it is easier to home and stops the problem of racking etc. Just a thought!
Quote:
Originally Posted by Clive S
I haven't but I suppose I could easily use one keeping the same design. In fact, I'm not sure how I ended up with two motors in the first place...
There are pro's and con's for the two systems I don't think there is much difference in cost between the two.Quote:
Originally Posted by biketrialsdave
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With two motors you will need two homing switches and a controller that can do the slaving correctly and also have the alarm outputs on the drives working in case one motor stalls and then the other will rack the system.
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Dean (Jazzcnc) usually uses one motor but I think on the machine he is now using it has two.
I use two motors and I am happy with it.
Yes it has but only because I inerited the machine it probably wouldn't if I built it my self.! . . . Thou It's just on the edge of too big for belts so maybe not.?Quote:
Originally Posted by Clive S
On large machines 2 motors make more sense because the belts get messy and custom lengths. At this size and with this design then I'd 100% be using belts.
It's only slightly cheaper in cost but much more reliable and stable in use. Can make full use of the machines potential and not worry about screws running out of sync with each other.
If using 2 motors then the ONLY way I'll use them is if the drives have Stall detect with fault output to E-stop the machine ie: EM806 or AM882 . Also external motion control card is prefered due to higher work load. (Personaly I won't use the Parallel port on any machine)
Hmm maybe I will stick with one motor and use a single large belt. I don't think it will require much modification (whilst still having the potential to run 2 motors in the future). Just need to make sure I can tension the belt well. I'm thinking of a simple idler pulley which I can slide in a slot.
You will need to make sure there are enough teeth engaged on the pulley with the belt. Also if you want to put material through the back of the machine the belt would have to be routed accordingly.Quote:
Originally Posted by biketrialsdave
Something like below? The bottom idler pulleys on both sides sit in slots for adjusting tension.
Attachment 16952Attachment 16953
You don't need to spend money on pulleys just to use them as tensioners.
What ability have you got for machining the aluminium? If only basic tools like me then you could probably lose some of the pockets. Would help with adjustment later too ?
Too many idlers drop try to keep to a minimum you'll get away with just one. Belt will be above the profile but doesn't matter because you'll want to cover it up anyway.
Attachment 16969
I only went for more idlers to keep the belt beneath the extrusion...maybe I'll have a re-think.
On a side note, starting to look at my electronics setup. I think these motors look reasonable?: SY60STH86-3008*
I've gone with your suggestion Dean but kept the slots in the plates so I've got flexibility in the future.
The cover needs work but looks like this now. It's starting to feel like the ends in sight!
Attachment 16996Attachment 16997
Hi Joe,Quote:
Originally Posted by JoeHarris
I'm going to put an RFQ up to get all the pieces machined. If only I had a mill to start with!
Word of warning before commiting fully to this route.? Make sure you can buy a long enough belt of the shelf other wise it means having custom length belts made. Not a Big issue but still worth thinking about now.
The available belt lengths may also mean changing the location of the tensioners so work out the belt length needed for how you have it drawn now and see if belts are available that will work.
Oh Happy new year.!
Belt comes in at ~1.56m. Ive used this place a few times and they have belts up to 2.5m:Quote:
Originally Posted by JAZZCNC
http://www.beltingonline.com/5mm-htd...ifo3qcvkih53b6
Happy new year everyone! :)
Happy new year chaps
reading this and the recent thread on controllers is tempting me back to the 3 stepper and belt option! I can feel another redesign coming on for 2016. Good luck Looking forward to seeing this project become a reality...
Jazz, is there enough engagement on the top right pulley? What's the minimum? you could add one more like this?? I Attachment 17005Quote:
Originally Posted by JAZZCNC
The spec. for HTD belts say make sure to have 5 teeth engaged. This is based on ensuring that with a sufficiently high load, the belt will snap instead of the teeth ripping off. This hardly matters to us, as we're not using the belts at close to their load ratings, however we do want to get good stiffness from the belts (especially with such a long best) so it seems a reasonable baseline to design for at least 5 teeth engaged.Quote:
Originally Posted by JoeHarris
Thanks for the info. With a 20T pulley I should have around 5 teeth engaged with what looks like a quarter of the pulley.
On a side note, I am currently looking at my bed plate design. I have put in a recessed hole to insert a standard kitchen sink waste hole. Is this OK or is there a preferred method? Also wondering if to move it to the corner and tilt the machine towards it...
Attachment 17031Attachment 17032
I've made some big progress over the past few weeks. Hopefully some photo's to come once a parcel arrives this week! :)
In the mean time, I'm starting to think about CAM software. I've looked at BobCad and CAMBAM. Not looking to spend an awful lot (for now). What would be everyone's recommendations for an easy to use package that will give me a good introduction to CAM?
You could have a look at Estlcam, the demo is free, and if you like it, it is only 50 Euros or so to licence it. It has a lot of features and I have just done my first job with it. There are video tutorials on t'Interweb. There are some aspects I don't like - I found it easier to start again from the dxf file if I messed up a toolpath (rather than deleting the toolpath - which seemed impossible) Maybe I will get better at using it, but if I find foibles which need to be sorted, I will address them with the author (Christian Knuell). In my correspondance about licensing, he seems happy to help.
Cheers,
Rob
Fusion 360 has been banded abut on the forum recently it is a cad and cam package and I believe free for a year and then you only have to register for hobby use.Quote:
Originally Posted by biketrialsdave
Ooh this looks very interesting!Quote:
Originally Posted by Clive S
http://www.autodesk.com/products/fusion-360/overview
I've got CamBam and EstlCam and both have their merits for me. If you've already drawn your object as a dxf and it's only simple machining then EstlCam is great as you don't have to join all the different lines that make up your shape. If you want to just draw something simple and then do the CAM on it then CamBam is good. I don't do anything complicated so can't comment for 3D shapes but for simple things (parts for RC planes, plastic thrust bearings, simple plastic parts etc.) both programs are easy to use and good.
I've not posted for a while but a lot has happened!
* I've received all the custom aluminium parts
* Ordered stepper motors and AM882's
* Ordered all ballscrews and linear rail for z-axis
Just need to make some more money before I can continue the spending! I'll put some photo's up soon...
It will be like Christmas morning!Quote:
Originally Posted by biketrialsdave
It certainly is like Christmas in my house at the moment...the girlfriend isn't too impressed with the number of boxes and smell of machine oil in my office though!
I am starting to get a little worried that my machine is going to be incredibly heavy. The parts for the Z-axis assembly alone weigh a ton! (Not literally, I am going to weigh them later). I just hope my 3Nm steppers are up to the job...yes, I know I should of done the calculations beforehand but I got carried away with buying shiny things!
Haha know the feeling. There have been some pretty beasty machines on here powered with those motors so I'd have thought they will be fine.. Looking forward to the picturesQuote:
Originally Posted by biketrialsdave
I've got a sodding great big 40mm front plate that my 2.2kw spindle hangs off and my 3Nm stepper whizzes it up and down no problem so you'll be fine!Quote:
Originally Posted by biketrialsdave
That's re-assuring. I've just done some quick calcs and it looks like the steppers will be more than up to the job. Of course, it was an educated guess! :emmersed:Quote:
Originally Posted by njhussey
More big steps today...cleared a big space in the shed and measured up ready to build my workbench/stand!
On a side note, what method does everyone recommend for finishing aluminium parts? Some of the larger parts I had machined for my router are not milled on both sides and so are dull and have the original "stock" finish (some have lettering etc). I want a finish which is durable and ideally helps oxidising. Anodising would be ideal but I think that's going to be a little price and not something I can do myself? So this leaves me with: Polishing (if so, what's the best way and will the finish oxidise over time?), spray painting, powder coating, other plating??
Thanks in advance!
It's bloody tool not a Pimp My Ride.!. . . :joker:. . . . . . Which is bit rich coming from a Bloke who's spent quarter the day Plastic coating parts for sexy little router he's finishing off. . .:hysterical:
Pimp my CNC!Quote:
Originally Posted by JAZZCNC
:beguiled: I think I'll use some 1000grit sandpaper then see if I can replace the grinding wheel on my cheap Aldi bench grinder with a polishing one.
I've polished a few bits of aluminium by starting with about 220 grit and a random orbit sander then going up the grits as high as possible before finishing by hand. I don't really think it's worth it though as aluminium is so soft it scratches again in five minutes. I suppose you could spray a lacquer on it maybe.
Hmm I think I'll do a 'quick' polish but nothing overboard.
While I'm thinking about it, should I be using threadlock on all my parts? Or will torquing to the correct value be enough?
Also, do I need to remove all the machine oil from my new ballscrews before using them?
Ahhhhh panic!!!
I thought things were going too well... I don't know how I've missed this but the 45 series rexroth extrusion has 10mm diameter holes for M12 screws on the ends. For some unknown reason I've designed my aluminium gantry sides for M6!!! I've seen you can get an M8 "cutting bush" which reduces the bore. Would my best option be to use these and get the side plates drilled out to M8?
=(
It would be much worse the other way around! Why don't you just increase the size of the holes on your end plates to take m12? Or am I missing something?Quote:
Originally Posted by biketrialsdave
I could do this but M12 socket caps look massive and don't leave much material thickness. Perhaps I might have to compromise with M12 button head bolts and not countersink them?Quote:
Originally Posted by JoeHarris
What plate thickness have you got?