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19-02-2020 #1
I stole it from Joe, who I'm sure stole it from someone else. I'm reliably told it's called development!
Great progress Ryan, it's coming along.
Jazz's comments are spot on, and also your BK nearest the motor is back to front. Mention to Fred that your dimensions are for the screw part not total length else you'll end up short!
I'd recommend an F length of 30mm on Y and Z to give more room for those pulleys. Don't know if Jazz was saying 25 for the X couplings or the pulleys? Either way just gives more room to align that pulley.
I've noticed your gantry vertical plates are wider than the distance between carriages - the angle continues further than the carriage. Might be worth trimming that because it's essentially cosmetic in its current form and will be costing you when you order the plate.
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20-02-2020 #2
Thanks Andy - feels like the design is almost there now, drawing in CAD certainly makes things easier to tweak/measure and figure out what should work.
Yes good shout on the gantry - I've reduced the width slightly (50mm approx) so it can be cut from a smaller piece of aluminium.
Just waiting to hear from Fred @ BST , so thinking about how I'll actually machine the pieces now.
Have you found printing 1:1 and sticking to the piece worked well? Also what contact adhesive did you use there?
I've bought some centre drills / counterbores to test out . Also thinking to get a metal cutting blade for the large wood bandsaw to cut the angle. That or a blade in mitre saw but feels a bandsaw would cope more..
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21-02-2020 #3
Yeah it was a low-tech solution that worked quite well. Can get messy though, recommend some cellulose thinners and a rag on standby to wipe the other edges of the piece you're spraying, and obviously do it on a waste surface like cardboard. I got the wife to cut the printed bits out - shes a little bit more artsy and careful with a pair of scissors. It was then mainly a case of alignment as you put it on, trying to get a straight edge aligned with the edge of the metal. We found spraying half then putting on roughly worked well as you had a couple of seconds to adjust the paper slightly. Then fold over and spray the other half, and then flatten out.
Used Evostick Impact spray, but I'm sure any contact adhesive would do the job. This one is a bit costly, I probably nicked it from the in-laws....
https://www.amazon.co.uk/Impact-Mult.../dp/B0095RFILA
Helped a lot with the marking out. I used one of those push down centre punches, but others have used optical ones which look really good.
When you're finished drilling on them, get some lighter fluid to help remove the paper and contact adhesive. That was a nasty job... Then shine with scotch-brite.
I love the counterbores I got. Great little tools. Centre drills didn't really work for me, I just ended up starting everything with a 2.5mm.
I used a crappy old table top wood band saw, and it worked okay. Just get a decent blade. I remember learning that you want approximately three teeth in contact, and I was cutting 10mm and 20mm Ali, so I went with approx 5mm pitch blade. Slow but steady, lots of cutting fluid.
However, I only used that for un-important edges. I got Aluminium warehouse to do the main cutting to size and just cut pieces in two where they had to be ordered as one piece due to minimum piece sizes. Where I had to cut a piece that mattered, I'd use Aluminium warehouse's edge as the mating side. That way all the mating surfaces have square(er) edges - the bandsaw cut edges needed a fair bit of sanding afterwards!Last edited by AndyUK; 21-02-2020 at 12:14 AM.
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28-02-2020 #4
So the build has officially started - I should probably convert this to a Build log if that's possible!
So the profile was joined using the self tapping M12 core screws, where the head slots into the 10mm profile slots and a hole is drilled though the profile to allow the T50 key to be inserted and tightened. This worked OK but I managed to almost break my wrist using a cordless drill and even a (cheap) impact driver struggled! Got there in the end and re-enforced with brackets.
I don't have any precision measuring tools at this point, but using the digital angle measure is 90.0 degrees on all angles and to 1mm across all dimensions.
Issue #1 - In my haste to add an extra piece of profile to my order (to have an L shaped gantry profile) the 2 profiles have different slot spacing. As far as I can tell the main issue is joining them. If these are joined simply by using the side gantry plates and socket head bolts to hold the pieces in contact is that a terrible idea? Could it be enhanced with some strong adhesive between the pieces to compensate. Really wan't to avoid wasting money on the extrusion if I can help it.. Any ideas?
I've also placed the order with BST Automation - Thanks for the recommendations. All smooth so far, Fred seems very responsive and helpful. There are expected delays due to the coronavirus but it sounds like production is just slightly slower then usual.
Only linear motion components so far - 1610 ballscrews and 1605 for Z. 20mm Linear rails and Carriages. Flanged Type for X axis for stability as I'm using a wide plate.
For the blocks which will mount to carriages - Is Ecocast type aluminium recommended here? Quite pricey for 50mm thick block so want to be sure it's worth using this.
Also thinking of what you mentioned Jazz - adjustability. Would slightly oversize holes be the usual way to achieve this?
On electronics - I'm considering Hybrid steppers now, certainly on X due to the dual X motors and potential stalling. Any recommendations on models here?
Thanks!
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28-02-2020 #5
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28-02-2020 #6
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28-02-2020 #7
It's not the best of ways but if you bolt the profiles together along there length as well as the ends it should be ok. Obviously, because the slots don't line up you won't be able to use the slots to lock together but you should be able to drill and tap them together from underneath with a few bolts.
Don't use adhesive.!!
Cast plate isn't required but the plates must perfectly flat with parallel faces and exactly same thickness on both sides of machine. Rolled plate isn't flat or with parallel faces so unless you machine it flat and parallel then ground plate is your only choice if you want it right. Why 50mm thick.?
Try to keep the holes to correct size if possible. Only make oversize if needed.
When I say adjustability I mean don't machine plates with slots etc that lock things together unless the whole machine is built this way and on an accurate machine. Adding plates or brackets that allow adjustability is always a good idea. When making plates etc then adding slots rather than holes can help in some places but depends on machine design.
One of my methods is to use slots to allow adjustabilty then when it's all setup I'll lock it in place using tappered holes and pins.
Wouldn't use anything else. These work well and allow AC or DC with voltages upto 70Vac or 100Vdc. This means you'll get good speed and with 5.5Nm you've plenty of power.
If you go for the lower powered motors just check the drives Max voltage because a lot of them are 50Vdc Max which will limit your speed.
https://www.aliexpress.com/item/3279...44bf3421SaYv5O
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01-03-2020 #8
I did some more thinking on 2 profiles with different spacing - as the 2 do not need to align on the face in the design, I can offset the top piece by 5mm so at least the front slot is in line, then bolt/tap the rear.
OK great - I'l either go for Ecocast or see if I can get it milled. Its 50mm thick as the block is intended to add some Z clearance for the gantry. Without it clearance is only about 100mm, so takes it upto 150mm .
Hybrid Steppers are slightly more reasonable price then I had expected Vs standard steppers. Looks like the LC60H2102 (4.5Nm) and LC60H2112 (4.8Nm) both also support 100VDC with the same LCDA86 Driver, although strangely are twice the price as the 5.5Nm from what I can see!
Would the 5.5Nm be overkill on the Z axis ?
I noticed the 5.5Nm has a 35mm shaft and keyway, which should help with pulley mounting. How does that work with direct coupling though, a keyway and standard shaft coupler?
Thanks
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06-03-2020 #9
700 x 500 x 250mm steel cabinet arrived today from TLC. Very solid and heavy @ 20kg. - hopefully everything will fit in based on previous builds on here! I see Andy had 800x600 which had a little space spare.
While I wait on the linear motion parts from BST - electronics are being planned, really steep learning curve here for me and hoping I can figure it all out with some of your help.
With the LCDA86 driver Jazz recommended, what voltage would be ideal. Its up to 100Vdc and I see a few people have used 68V - so would give some margin but would that be at expense of too much power?
LC60H2112 is listed as 5.6A current, so with 4 motors do I need 22.4A x 68V = 1523VA PSU? Sounds huge.
I'm trying to take each component in turn and map out the connections - first the driver to AXXB-E. Except for ALM I can't figure out which other terminals need to be connected if at all ? For example ENA+, Pend, and the Encoder E* ones.
AXXB manual refers to just Step and Dir.
Edit..Just realised VCC/GND wrong colours on that IMG..
Thanks
RyanLast edited by CNCRY; 06-03-2020 at 12:29 AM. Reason: added note
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