MPCNC Version 2 -opinions-

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#1

Okay I just can’t come up with an easy way for me not to have to build 3 machines for the 3 size conduit that is out there. Adding hardware and cost seems like a bad trade off. So I ask for your help, the people that get to use there machines more than I do!

So here is my thinking.

  1. The original was designed to be 3d printed, and possibly injection molded That is why I tried to keep the unique number of parts down, plan was to even use the middle joiners x’s 4 instead of the middle ends. I also thought, foolishly, that all conduit was the same size worldwide.
    Find another rail, unique part count doesn’t matter if we are printing it anyway.

  2. As it is now it is dirt cheap and works better than I had ever hoped. People can continue to use this without feeling like they are missing out if they don’t want to spend a bit more for a slightly better version. Conduit is nice but we can do better.
    Second version can cost bit more without pissing anyone off.

3)More rigidity = faster and more accurate. We are carrying a much larger tool than I had originally designed this for and who doesn’t like faster?
Slightly larger diameter tube/rail will benefit the most here, as well as some design tweaks that I learned from the first.

So I am thinking Stainless Steel rails, and a redesign. Nothing drastic same bearings, steppers, controller, same basic layout. Good?

Stainless has better wear properties, more rigidity, but what size? At least 25mm, what size is available in your corner of the world? I can probably find a good source that can ship a kit worldwide and perhaps even ship custom kits. But I am not trying to spend hundreds on rail when the previous stuff works great for $7.

  1. Name, Need a name for this. It is a cnc platform, a multi function machine. Stick with the original “Melvin”? Not fond of V2 or version 2 or beta.
#2

love the thought of another project, been having a lot of fun with the current version. Living in Australia had a issue with the 25mm tube and have been using aluminium 6061 grade tube with little ware but still yet to give it a hard time.
priced stainless and was way to high to even consider, how would aluminium extrusion running on 608 bearing and nylon rollers go?? i know price would be high but don’t know as high as stainless, might also be able to get larger spans on square/rectangle extrusion
looking forward to hearing more responses

#3

I was thinking alu extrusion too. maybe even a gear lock design to help stabilize. you still use the conduit for the middle z, roller setup. but run it all on 2040 or 2060 extrusion with a tooth gear roller instead of the belt driven setup. maybe smaller diameter pipe for the z drive to shrink down the z package and give a little more build volume.

#4

Tooth driven how? Sounds slow and likely to skip steps. I’d go leadscrew or ballscrew but they are both expensive and slower than belts. Most 3d printers use belts for the x and y axis for speed.

#5

my thought is if he goes to aluminum extruded rails and wheels sliding along those rails then he is just like 105462 other make your own CNC machines out there, for the same price as they are.
i like the design of this. the locally sourced parts, the option to print my own.
I doubt i would have made this if i just bought a kit with parts, etc for $500 and built it.

maybe thats just me :slight_smile:

#6

Square extrusion takes too much hardware, you need to touch all 4 sides instead of just 3 with tubes or hex.

Gears, leadscrews, ect all have backlash. Software compensation is crappy at best.

I really like belts. I think I will be belt driving the z as well with a multiple pulley system? Probably not but I would like too and will be trying it out.

#7

Yup, I agree. I just want to make some improvements and don’t want to maintain multiple versions. It really kills motivation when you know you will have to do some thing a few times.

What else can be easily sourced though? Just larger conduit? The stuff is nice for milling but I am seeing it’s weaknesses with the laser etching that is going on. Closet rod is cool and fairly inexpensive but the sizes are all over the place. That is how I keep ending up at stainless. The nice hand rail, boat rail, stuff is thin walled and in a few standard sizes.

#8

would it be worth asking all corners to find a common tube/pipe/rod size, us trouble makers down in Australia can get 25.4mm/1" off the shelf.
agree with the other comments re staying unique re staying away from the common alu extrusion, after my original post re alu did some research and yeah defeats the purpose of this awesome project. maybe larger diameter tube for lager spanning options.
1 question what are we really trying to fix apart from maintaining 2 designs

#9

A few things, I hope.

More rigid. I designed this for the small lightweight rotary flex shaft grinder, turns out the dewalt and a few others are a better choice. I have 2 new center assemblies not sure which one is better yet I printed the prototypes with light infill so they both flex. Need to reprint and give it another test.

Ideally multiple size tubes- but doesn’t really seem feasible with this geometry. So a single size is the tradeoff.

Less parts or faster printing? I hope

Smaller foot print, maybe, a little less dead space.

Less unique sized hardware, for easier assembly.

Better rails for us heavy users. The conduit from my first machine has been rotated several times. And I think the smoothness of the rails is having an effect on the laser etching resolution. And the stuff that comes off the rails as they wear is making a nasty mess of my machines.

I could keep going. Really this is just a better version for those that want it. I am leaving the other ones up I think they work great.

I guess I can just improve the machines we have, right? People can buy 25mm stainless and use that one and I could just redesign some of the parts I want to change…
Maybe I should do that. Just make some changes. Cool! Nevermind, maybe I should take this thread down.

#10

Have you found any good sources for the IE version Stainless steel sourced from the US?

#11

Well I found some but I don’t want to pay that much. 25.4mm (1") is a little less than a 1/3rd the price. Grrrrrr, I don’t want to make a 3rd version.

#12

what countries can not source 25.4mm cheaper than 25mm

#13

Good Question.

Drop the 25, for a 25.4…?

#14

I’d vote for 25.4 - Australia
can you see any benefits in going larger again???

#15

I really have not seen many large builds. As far as I know I get asked once a week about it but no one has actually built one. I am pretty happy with a smaller build. I can see some people wanting to cut full sheets 4’x8’, but really that is only a few people not the majority. With some mid spans support I still think it could cut full sheets as is of wood.

So larger rails is just a larger footprint for us people who want smaller machines. Best of both worlds?

#16

I’d like to go all stainless as well. but I have to find a good cheap place to get it. You should be able to find 3/4emt in stainless at an electrical supply house, but I am unsure of the actual dimensions (larger, smaller?). maybe instead of making vast improvements just up the size of the motors…

#17

I’m happy with the power we have. If you need more you can just turn up your drivers. We are under powering our steppers!

I want more rigidity and precision. Steppers won’t change this.

#18

You’re not going to get much more precision and rigidity than where you’re at right now. unless you want to go to hardened stainless rods. At 25mm and 30in lengths, well i don’t know what that would cost. if you go any smaller on the emt size you will lose rigidity. if you go any larger than 1" maybe 1 1/4" You’ll start to lose rigitity as well. and cost effectiveness. keep focusing on making your awesome designs better.

#19

In Italy 25.4 is hard to find…

#20

What sizes do you have available? In conduit and stainless?