Most excellent machine build ,I enjoy very much the videos and I hope one day I will make good use of all thiaw tips you shared!
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Most excellent machine build ,I enjoy very much the videos and I hope one day I will make good use of all thiaw tips you shared!
Thanks Andy, Nick. I'm just a hobby machinist and just passing on what I have learnt along the way. Glad it was all helpful.
OK so yesterday I managed to take some measurements for the X and Y stiffness of the new Atlas Mk4 machine.
The machine was positioned so the gantry was half way along the X axis, and the Y axis was positioned at the mid point of the gantry. So the X and Y positions represented worst case. The Z axis was lowered 50 mm from home in a typical machining position.
I used a digital luggage scale with a hook on the end to pull on the spindle just slightly above the collet nut (6mm end mill was inserted), while a DTI was pointed to the round section on the collet nut just above the flats.
5kg load was applied (~50 N) and the reading in for both X and Y was somewhere around 0.01 - 0.015 mm. I'm wondering how reliable this reading was given the needle barely moved and 0.01 to 0.015 makes quite a difference on the stiffness values. I guess I really need to buy a 0.001 mm DTI !
Anyway, for Atlas mk4 this works out at:
X between 3333 and 5000 N/mm (0.015 and 0.01 mm respectively)
Y between 3333 and 5000 N/mm (0.015 and 0.01 mm respectively)
My previous mk3 machine was:
X 1000 N/mm
Y 1250 N/mm
So up to 5 times stiffer. It certainly sounds different when machining and as you might have seen in the videos you can certainly take a good cut so long as there is some lubrication. I didn't measure Z this time as it was a bit awkward Vs the previous machine.
I did not have long to explore further but just before I finished I quickly pulled on the ballscrews when the DTI was still on the spindle and could make the needle move a bit. So maybe the limit is the stiffness of the small AC bearings in the ballscrew housings, or come to think of it they might be the deep groove ball bearings? Anyway I think as it is all working well I should stop there otherwise I will never use it to make something !
Thanks a lot for the stiffness measurements!
I had to put aside the research and design for my new cnc, that's why I didn't bother you.
If you accept challenges, here is one for you, as I see you are an expert at sheet metal bending: dust covers :joyous: Attachment 25475
Re homing/limits, I have set in Mach3 the sensors for both home and limits as well as setting soft limits with the min. max. travel. It works nice, stops before "hitting" the sensors in jog mode and I get limit warnings when g-code is out of the machine travel. With this setup I have never hit the hard limit switches so far.
Hi Routercnc I've just been going back through one or two of your videos when the dire internet here allows, and I'm curious about one of the things shown in episode 23, where you square up the gantry.It looks like you're achieving this by having independent limit/homing switches on each of the horizontal axis ballscrews, but doesn't this leave the whole assembly under quite a bit of tension?? or do you home it with the screws slackened off a tad then tighten?And does it mean you need to have separate drives from the control software for each of the steppers?
Although it's not assembled yet I'm trying to figure out how I will square up the gantry on my little machine, bearing in mind that my gantry is quite short (~600mm) and a very rigid bit of box section.
Thanks, Trevor
That sheet metal looks like a challenge. I guess they are concertina type? I think Chris Deprico (?) on YouTube made some and it looked very fiddly making the X bracing supports underneath which guide it.Quote:
Originally Posted by paulus.v
Yes I’ve since added soft limits and it works well
Hi Trevor
Yes you can only use this to square up a mm or so otherwise there is too much tension. You need to make and assemble it as square as possible first. Depending on the design you might be able to slacken the gantry bolts and square it up using separate home switches then retighten as you suggest.
I had to be careful with mine as to do independent homing I needed to switch off slaved axes temporarily. This meant my Z motors were also no longer slaved (I have 2 on Z) so after homing X I switched slave back on and now usually just home off the left sensor with the motors slaved. I check each side with callipers to ensure they are still the same distance from the end plates.
Yes separate drives are required plus a spare axis on your break out board (usually A). You can’t do this trick from a single motor with belt coupling to the other ballscrew and would need a way of making tiny adjustments on one ballscrew relative to the other mechanically. Probably the grub screws holding the pulley onto one of the shafts
Thanks very much for the clarification. I'm not so worried about squaring the gantry on the horizontal sense (having it parallel to the bed) - I have a big digital height gauge so can get that initially set pretty good, besides mine's single motor on the Z.- It was more the X,Y squareness for which the only "old fashioned" tool would seem to be a fairly huge and vastly heavy 3 way angle plate. I'm running twin motors/screws on the long axis (which I call Y since I look at it from the front), but was going to simply parallel up the inputs to the drivers, in the light of this maybe I need to have a bigger BOB or a bit of switching.
Would a 3.1Nm motor really find it that much of a challenge to drive 4 ball nuts all engaged at the same time on your Y ?
Super cool of you to do what your about to do btw :wink:
P.S Don't forget we have an open source section/forum.
I'm not sure if I'm honest. To drive 4 ballnuts without pre-load would be fine I think, but when the ballnuts are clamped together there is an extra load to overcome, and the Y/Z is pretty heavy. Is it worth the risk to have missed steps on a critical job? Not sure.
Decided to leave it like that and put some pre-load between the front and back ballscrews instead.
Sending pm shortly . . .
Hi Lee, pm sent . . .
For anyone interested here is episode 26 of the CNC series giving an overview of my humble but functional CNC controller.
Also, for anyone who likes oscilloscopes there is a review of the Hantek DSO5102P oscilloscope supplied by Banggood.
Then right at the end of the video is a short montage of the controller build.
https://youtu.be/KFPSKisqVVw
If you see this Lee PM sent . . .
I've had many requests for the CAD of this machine. I've also had requests for narration so I decided to put together a 3 part mini series to show a shorter version of the build for new viewers and also explain how the CAD can be downloaded for free (explained at the end of part 3). If you have seen the original 27 episodes of this build there is no new material, but the narration may help with explaining how I approached it.
Here is part 1 of 3:
https://youtu.be/FQDzNQ-sZA0
Like buses you wait for ages then 2 come along together. Here is part 2 of 3 of this miniseries. Again, if you have seen the original 27 episodes of this build there is no new material, but the narration may help with explaining how I approached it.
https://youtu.be/3XREfXwKxKw
Again, if you have seen the original 27 episodes of this build there is no new material, but the narration may help with explaining how I approached it.
Part 3 of 3 . . . .
https://youtu.be/v1YXjxckv4U
The major benefit of this design is the ability to machine a workpiece that is way larger than you could fit in a conventional fixed gantry mill. You could place one end of a 20' beam on the bed and machine one end, or even machine the entire length in stages.
Since I have an air compressor . . . I decided it was about time !
https://youtu.be/tSb5bdfHPyg
As per the YouTube comment, here are some pics of my cool mist set up, but for my manual milling machine.
Attachment 31119
Attachment 31120
Those water filters will take 8 bar it will probably say that on the box and the little screw on RH side is for letting the air out (priming) when being used as a water filter .
Nice vid.:thumsup:
OK good to know thank you
I decided to do some of my own testing . . . here are the results:
https://youtu.be/tc2L6QT_G6I
About time I built this thing !
https://youtu.be/xZEE-I_cbtc
I'm not looking to start a new project any time soon, but I'm planning ahead for a new or repaired WC spindle. In my last video (above) you probably heard the noise as the spindle ramped down. It makes a rough noise when it goes through a resonance at a few 1000 rpm or so.
When running at 12,000 rpm it sounds ~OK but it does not bode well for the life of the motor. When stationary if I grab the end of the spindle I can feel a very slight amount of play so this is probably the cause. It has been doing this for a while now.
I think these spindles have 2 angular contact bearings at the nose end, and one ball bearing at the far end. It might be a case of sorting out the preload as I believe there is a LH threaded bolt at the top end which may set this. Or they might just be deep groove ball bearings at the nose end, not sure on this model. Maybe I can just install new bearings and that would sort it out.
This is a 1.5 kW Chinese WC spindle which has been doing great service since about 2008/9 (?) and has cut a lot of aluminium, up to 20mm thick. So it has had a fairly hard life considering, but I do need to start looking into the options in case it goes downhill quickly.
I'm right at the start of the planning, so it is early days, and replacing the bearings would be an option. However, the spindle has always been the lowest performing part of this mk4 machine and I think it could handle much more power, especially with the new mist system.
After a few hours research I've got this table so far (obviously still looking into the options and specs):
Attachment 31178
I'm not looking for an auto tool changer, I'm OK using ER collets and manually swapping tools over. I want to cut aluminium mainly, and some steel parts (using small cutters probably) such as keyways. Any thoughts and experience welcome, thanks.
I’ve looked into lots of options and one of them is to go for a 3kW motor (Chinese wc spindle) via a belt drive onto a DIY cartridge with an ER32 collet. With a ratio of 2:1 I get x4 the torque of my 1.5 kW direct drive spindle and 9,000 rpm. Or 1.5:1 I get x3 the torque and 12,000 rpm. I’ll need to check the max rpm of the bearings I use for the cartridge.
Anyway only planning at this point so my question is can I run the 3kW spindle off a standard UK circuit (13A). The spindle claims it runs up to 10A which is OK on paper but I wanted to check any real world usage, thanks.
Finished !
I got the mixer block modified to take the blast system - and then I broke the locline fitting. Still, managed to get a very basic bit of machining done and looks promising so far. Not a very in-depth machining session at the end, just a quick check and I think this is going to work OK.
https://youtu.be/LVnqZSLWL3M
Another option might be to go for a constant power spindle, i.e. one where the torque increases as the speed decreases/ I have one from Jian-Ken and it chomps through ali nicely.Quote:
Originally Posted by routercnc
Do you have a link?Quote:
Originally Posted by Voicecoil
was having a look the other day
https://www.jian-ken.com/constant-to...otor-spindles/
Regards
Mike
http://www.jian-ken.com/high-speed-m...r-spindle.htmlQuote:
Originally Posted by routercnc
Ok great thanks both, more to consider . . .Quote:
Originally Posted by Voicecoil
I had someone ask about the ProfiCAD electrical diagram I drew up for the AXBB-E electrical re-work on my mk4 CNC machine. It's been a while since I drew but it made sense at the time and seemed to work. By all means use it for ideas and as a start point but ultimately you need to be happy and confident with what you are doing to ensure it meets your requirements.
I've uploaded this as a zip so you will need to unpack it.
Attachment 31774