Go Down

Topic: Desktop CNC advice request (Read 3570 times) previous topic - next topic

DangerToMyself

Well, in my search for a decent machine, I am really leaning towards the MillRight M3 minus the Router and mount. I really don't want to use a wood router to do the job of a spindle. Not to mention the noise a wood router makes. I know spindles can be loud as well.

Anyone heard anything bad abought the M3? Or with MillRight in general? Not real keen on the frame being made of MDF. But that could be upgraded later on to something more durable and stiffer.

ballscrewbob

#16
Oct 24, 2019, 09:38 pm Last Edit: Oct 24, 2019, 09:56 pm by ballscrewbob
Not keen on the belt drive either to be honest or the Vee rails.
(explanation) Real CNC machines tend to always use direct drive or a small pulley to direct drive not a full belt for the whole travel. It is also less noise overall too. Also there is no SLACK to take up that can introduce some positional errors.

If that's about the size you want to start with then I would say look for something that has direct drive from the stepper and runs on at least 12mm linear rails. (most about that size will)

I know the chinese ones look crappy but the frames tend to be aluminium and very sturdy.
The "TEE" bolt frame can take many additions and  lend themselves well to modifications (speaking from experience LOL)

Mine has had some plywood added and an extra PSU for the better spindle and some extra controls are mounted on that along with fans (old computer) on each side in PUSH PULL mode to get the fumes and fine dust to one side for easier clean up...

I agree on no router approach for the smaller machines as the spindles are quieter.
But you should look for a minimum 500W (300W would be an ok starter) with an ER11 collet on it.
And ER11 chucks up to 1/4 and 6 MM although you would find a lot of the smaller bits use 3.175 mm regardless of size.  You WILL break some of the smaller tools until you get to grips with speeds and feeds so having extras is a bonus.

Don't expect to use STD router tools on small stuff unless you are quite careful.

Mine is a bit of a Frankenmill with the modifications but it does what I ask of it and I can swap it back to its original config without too much hassle apart from the Y and Z axis that failed (3d printed).

Bob.

Addendum.. In another life I installed ballscrews to CNC lathes and mills and was also a service tech for a couple of CNC machine suppliers hence the nic.
It may not be the answer you were looking for but its the one I am giving based on either experience, educated guess, google or the fact that you gave nothing to go with in the first place so I used my wonky crystal ball.

DangerToMyself

Addendum.. In another life I installed ballscrews to CNC lathes and mills and was also a service tech for a couple of CNC machine suppliers hence the nic.
That makes me appreciate your insight all the more!

I looked at the Chinese CNC machines like this one.  And was putting thought into how to recreate those printed parts in a stronger material. Or how to swap them with better parts.

Aside from that, and the cheap spindle, those machines seem somewhat solid. There's even a vid on YT where a fella machines aluminum with his. No way near as fast as the MillRight M3 was shown to do though. That said, the MillRight had a top of the line spindle and a high quality mill/bit. (Still working on terminology)

The ability to machine aluminum is not mandatory for me. Just a bonus.

DangerToMyself

The machine I linked above was not the one I was eyeballing. It has plastic uprights. This is similar or maybe even the same as what I was looking at.

ballscrewbob

#19
Oct 25, 2019, 06:20 am Last Edit: Oct 25, 2019, 06:26 am by ballscrewbob
Those grey plastic lumps are what will fail eventually.
Luckily for me I saw it coming and used the machine to make its own replacement parts somewhat.
A few suppliers offer upgrades to those parts and for the Z its often worth it as you will probably end up with more Z travel.
That extra Z travel can come in quite useful too.

If you have somebody who can machine HDPE or aluminium that would make great replacement parts.
If not and you are handy (and accurate) with wood then a suitable hardwood makes just as good a replacement.
My spare parts came from a hardwood skid and I used the machine to do most of the work but simplified that "U" shaped bit to just a block that carries the bearings and lead screw. Then added two right angle plates I found at the hardware store to carry the rest of the assembly.

But see all those empty T slots on the side that just beg for something to be mounted like a nice piece of ply so you can move the power supply and electronics to a better area and give yourself room to add some extra controls and gadgets.
Also acts as a guard sort of to keep a lot of the sawdust more inside the machine.

Mine was a 3025 with a 50mm Z now its a 3025 with 170 Z and a plethora of electronic bolt ons.
Once you have one in your hands then you will quickly see which bits could have been made better or what you need to add on.

BTW if you can be patient enough with waiting times for delivery then look at Aliexpress or even Ebay as Amazon tends to be more expensive for this game all round. Even my tooling comes from Aliexpress.

For tooling try avoid dual flutes and go with 4 flute preferably without the hole in the end for coolant and if you can find them the ones with slightly offset cutting edges on the bottom.
I got some 4mm ones a while back and am amazed at how much deeper I can go for a pass and how much quicker too. Not broken one of those yet either...Rough out with end mills and finish off with a ball end.
Although on occasion I finish with 1.0 mm END mills but you have to be careful with those.

BTW despite my CNC background it was all mechanical and I never programmed them so all this was a learning curve for me.

Will throw a couple of pics up when I get a moment that may explain better than I do.

Bob.

It may not be the answer you were looking for but its the one I am giving based on either experience, educated guess, google or the fact that you gave nothing to go with in the first place so I used my wonky crystal ball.

DangerToMyself

I was actually contemplating using epoxy resin to cast blocks large enough to machine down. Stuff sets hard as a rock and cuts and drills pretty well. Would have to test if a 3018 can mill it though. I guess a lot would depend on the spindle and tooling chosen.

I linked to the one on Amazon only because their links tend to stay active longer. eBay  was where I was looking though. And you're correct. Much cheaper.

And I would love to see how you modded the Z axis. The Z travel is IMO the one of the biggest cons to these machines besides the plastic bits. Of course, my opinion is based on very, very limited knowledge.


ballscrewbob

#21
Oct 25, 2019, 04:53 pm Last Edit: Oct 25, 2019, 05:16 pm by ballscrewbob
Some poor pics of the mods.

The black brackets found at a hardware store. The lower one was modified to allow the spindle body to pass by





Extra parts used.

2x optical rod 8mm x 200mm long
2x flange mount for 8mm rod
2x end mount for 8mm rod
1x  8mm leadscrew 250 mm long
1x 8mm flange bearing.

Rest was scrounged from the Z failure.
You can also see some rubber strip I used to help damp the spindle noise but that has to be positioned carefully otherwise you will throw out the the tooling alignment.
Just had enough room on the machine to get most of the depth needed for the bearing holes etc in the wood with a long series 6mm end mill, and finished off on a regular drill stand.

Other pic shows the plywood dust catching and fan.
It will take two fans if I want as there is a plate over the second hole.

I would be wary of EPOXY RESIN as it has a tendency to fracture under stress. You will encounter stress in more than one way LOL.

Bob
It may not be the answer you were looking for but its the one I am giving based on either experience, educated guess, google or the fact that you gave nothing to go with in the first place so I used my wonky crystal ball.

DangerToMyself

I would be wary of EPOXY RESIN as it has a tendency to fracture under stress. You will encounter stress in more than one way LOL.

Bob
I really should have thought of that. I built an electric guitar for my son last Christmas and finished it with clear epoxy. Makes for one heck of a mirror shine when all buffed out. But he bumped it pretty hard going through a doorway and it popped a big chunk out. Was a pretty easy repair. Way easier than a paint finish.

I'll probably start out similar to yours by using a hard wood. Once I figure everything out I should say.

Just did the "make offer" thing on a 3018 on eBay. Have to wait and see if they'll go for it. Their original price was well below anything on Amazon. And I asked for another 30% off. We'll see.

ballscrewbob

30% less I would consider a bit of an insult so don't be surprised if you don't get an answer.

Good thing is the machine is capable of making its own spare parts in some cases.
Better thing is, you can design them without the flaws and some built in improvements.

There are some advantages to using hardwood on these smaller machines.

1. If you use the GRAIN to its advantage it can add quite a bit of strength.
2. It does help soak noise and vibration.
3. The size you are using makes it super cheap and affordable. (or in my case free)
4. Easy to make even if you don't have the machine to begin with. (my prototype was just done on the drill)
5. This is an important one. As you use grease to keep the bearings lubed that soaks into the wood and enhances the strength even more as it feeds the wood (so to speak)

Bob.


It may not be the answer you were looking for but its the one I am giving based on either experience, educated guess, google or the fact that you gave nothing to go with in the first place so I used my wonky crystal ball.

DangerToMyself

Quote from: ballscrewbob
30% less I would consider a bit of an insult so don't be surprised if you don't get an answer.
I heard back on that offer. Person said listed price was the price. No negotiating. Replied back with a higher price and asked why have that option available. Got a reply stating it would be removed from future postings.

Going to order one that doesn't come with the ER11 collet. But I'm also going to order a better spindle. Seems most of those I'm finding come with the collet.

I'm open to input on what to look for in a decent spindle. Of course, an ER11 is pretty much mandatory. And bare minimum of 300W. But looking for 400+.


DangerToMyself

Also, regarding the use of wood to recreate/modify the plastics. Thinking about using plywood layered together. That should take care of strength in just about every direction. Plus, I have plenty on hand. Thoughts?

ballscrewbob

#26
Oct 26, 2019, 08:18 pm Last Edit: Oct 26, 2019, 08:19 pm by ballscrewbob
Decent plywood properly laminated and glued etc would be a great substitute for just hardwood.
Probably marine grade as the glues used are better than regular ply.

Last spindle I got was this one.
Love it and extended the pot wires a bit so I could place it better.
Also fitted a proper switch rather than the wire jumper for on/off.
Bonus is that it will drop in to a larger machine because it has the MACH option too.
Sort of thinking ahead of myself LOL.

Bob.
It may not be the answer you were looking for but its the one I am giving based on either experience, educated guess, google or the fact that you gave nothing to go with in the first place so I used my wonky crystal ball.

DangerToMyself

Last spindle I got was this one.
That is weird. The one you have linked is one of two I have in my cart. The other one is roughly the same price but doesn't have nearly as much with it. Just the spindle, collet and driver. And now that I'm looking at them side by side, I think they're exactly the same driver and spindle. So, I guess it's a no brainier on which to delete from my cart. Still eyeballing others but seems like best bang for the buck. And most likely the one I'll order.

As I said, I really do appreciate you sharing your opinions/knowledge. I feel a lot more confident that I won't be just wasting money on something completely unusable.

I'm going to place my order today for the machine and the spindle and possibly a bit set. I think that should keep me busy for a time with delivery time, setup, etc.

I'll hit up LinuxCNC for software questions. And with any help I need getting it to actually mill a project.

 Hopefully, I won't have to bug you for a while!

Thanks again!

ballscrewbob

As for the mill set Might I suggest.

A couple sets similar to these.

And a couple sets of these.

Between them you would have a good starter set suitable for a good range of work.

You can always add to those later with more specialist ones.

Bob.
It may not be the answer you were looking for but its the one I am giving based on either experience, educated guess, google or the fact that you gave nothing to go with in the first place so I used my wonky crystal ball.

ballscrewbob

As for bugging me well thats what we are all here for one way or another.
Masochistic tendencies I think they call it LOL

Bob.
It may not be the answer you were looking for but its the one I am giving based on either experience, educated guess, google or the fact that you gave nothing to go with in the first place so I used my wonky crystal ball.

Go Up