Based on a lot of thinking and advices I have started a total redesign of my CNC.
Im going to use dual ball screws for the Y-axis + use a lot shorter “legs” on the gantry.. I think this is a better/more stable setup. 25mm mdf, 90x90mm Bosh profiles and Bosh Rexroth 25mm rail/block. Im not going to install the ball screw (1605) like this – only for testing.
-Have you considered the advantages that using a fixed gantry brings?
Good luck
If has been said often that your first CNC you build is usually not your last. Also, we learn more from our failures, than our successes. Until you’re knee deep in it, all the advise people give you is so much hot air. So you’re just going to have to wade in, and see things for yourself.
Those look like real nice linear guides to me. You should be able to get something real nice working with them.
Check the current draw of your drives control lines, if you’re driving more than one. You don’t want to exceed the capacity of your control electronics. Attempting to draw more current than is available is a leading cause of blew smoke escaping. You’ll probably be OK. But it is better to look before diving in.
I just checked a drive on my bench here, and it is only drawing 9ma. You could drive two of those on lots of circuits. But not all circuits can output 18ma. I know I setup the drives I made to draw 12ma. Two of those together would be quite a load on a lot of electronics. In fact when I dual drove them I fanned the signal out to a pair of buffers, to supply the current.
Theoretically one output could have just barely managed it. But I don’t like to push my luck that far. So just check, to see what you are dealing with. To be forewarned is to be forearmed. Asking for more often leads to having to do more to get it. CNC ain’t no soup kitchen. Free lunches are served elsewhere.
Thank tou for the advice - have not ordered any electronics yet, so I can buy the drivers… that are the best for my setup later
@Oyvind_Amundsen
I’m checking out some cheap Chinese TB6600 drives right now. They’re pretty good. I mean they’re really good. They’re powerful. You can definitely do worse than these
https://www.aliexpress.com/item/High-Quality-TB6600-DC12-45V-Two-Phase-Hybrid-Stepper-Motor-Driver-Controller/32608542477.html?spm=2114.01010208.3.1.kmPpfI&ws_ab_test=searchweb201556_0,searchweb201602_2_10065_10068_10067_10069_418_10017_10060_10061_10062_10057_10056_10055_10037_10054_301_10033_10059_10032_10058_10073_10070_10052_10053_10050_10051,searchweb201603_4&btsid=ee03e3a6-838f-4e0f-ba86-2433d842f5ca Although there’s better. But they’d cost more than 10 times the price. I doubt you’d need anything any better for your machine either.
As soon as I get done with my 5 Volt supply I’m putting them on my machine here. You should get one to evaluate. That’s how I did it. I bought a couple different drives, to see what I liked the best. Then I ordered more. These are the ones I liked.
Don’t let the price fool you, these are some runners. Although the max voltage printed on them is kind of low. I don’t know what that’s all about. I’m running them 2V below that and they’re still preforming great. So I’m not going to worry about it.
When I get my new PSU I’ll run them right at the printed voltage of 32. For me it’ll be fine.
This is not the end design, only testing, so not the correct lengths…
I consider something like this. The two X rails mounted on two 20x70 massive aluminum. On the gantry the sides I plan to use 45x90 profiles + a 11mm aluminum plate to make it stable.
Using this setup, I have 19cm from the MDF to the firs X-rail.
https://plus.google.com/photos/102309741047174439430/albums/6333078457767655265/6333078456393690402
@Miguel_Sanchez
They run at higher voltage. But at almost 3 times they price they offer little advantage to me. These other drives run as strong as I need. I take Chinese specs with a grain of salt anyways. I’d wear a full face shield before I put 48V through those drives.
@Paul_Frederick Higher voltage is your friend and the key to achieve higher speeds, which come in handy for decent rapids. But having used different drivers (both 6600, 542 and 860) I have found the 542 offers IMHO the best balance between price and performance for light CNC machines. (And for what is worth, I have been using these @48V for years without a fault at a shop where 50C is not unheard of).
@Miguel_Sanchez
Good to know. For my purposes these drives are more than adequate. They’re easily twice as good as the drives I use now. Which are fairly adequate as it is. I have other defects I need to take care of on my machine to be able to use anything better. Things that likely will never be addressed. I’ll save that for the next build.
I just got a PSU to use with these new drives and it sucks. It was supposed to be a 36V PSU and open it is 30.6V Loaded it drops to 26V.
So my old unregulated supply is better than it is. I don’t know what I am going to do about that yet. I know I’m not using this new PSU. But all of this just happened, so I have not formulated much of a recovery plan yet. I’m still in the pissed off and can’t think straight stage now.