[nalmeida]

Hi there guys, it's been a long time since my last post. Three years ago I built a Midi Router from Widgitmaster and I've been using it with great success since then.
Despite the midi being a great machine I'm in need of an even smaller machine that I could use at my office and I'm trying to plan one based on the Othermill. It's gonna have similar dimensions, just a bit wider, and will use the same principle.

I only want to cut soft plastics (styrene) and wax with the machine. No metal or wood cutting.

Now, I've been sourcing some parts and materials and would like to have opinions from the experts before I start planing and cutting the materials.

Like the Othermill I will use PE500 (HDPE) with 10 mm, since I will use the same cubic design I think it will be strong enough.

For the motors I plan to use Nema 17 with lead screws like these ones: Pololu - New NEMA 17 stepper motor with optional integrated lead screw
They say the precision can reach 0,04 mm which is good enough for me.

As for the electronics I was thinking about the TinyG from Synthetos wich connects to the PC through USB since I don't have PC's with parallel ports available. Also this seems a suitable solution for a smaller machine and seems adequate to control the nema 17 motors.

Keeping in mind that I'm looking for a bit of precision and I only need to cut soft plastics and wax what do you guys think of this mechanical/electronic combo?

[wizard]

Hi there guys, it's been a long time since my last post. Three years ago I built a Midi Router from Widgitmaster and I've been using it with great success since then.
Despite the midi being a great machine I'm in need of an even smaller machine that I could use at my office and I'm trying to plan one based on the Othermill. It's gonna have similar dimensions, just a bit wider, and will use the same principle.

Is that machine really that much smaller? Both machines seem to be solid attempts at a quality machine in their own right. However the Wigitmaster machine strikes me as a more conventional design and certianly is robust enough for your needs.

In either case though I would not be thrilled about running one of these in an office. The noise and dust would be a problem. If you do go the other machine route Id suggest totally enclosing the machine and even adding sound proofing. Obviously I don't know the specifics of your office but even in my home office the noise and dust would drive me crazy. Sometimes it pays to separate the two work environments.

I only want to cut soft plastics (styrene) and wax with the machine. No metal or wood cutting.

This does free you up to use just about any design out there and to modify something to suit. Given that it is fairly easy in a desktop machine to make the machine very stiff which can be a significant advantage. This is especially useful if you intend to move beyond a deemed as a spindle.

Now, I've been sourcing some parts and materials and would like to have opinions from the experts before I start planing and cutting the materials.

Like the Othermill I will use PE500 (HDPE) with 10 mm, since I will use the same cubic design I think it will be strong enough.

Maybe, I haven't built machinery with such material so I can't help based on experience. Obviously your machining isn't the most demanding so it probably would be fine. I do wonder what a machine like this built out of aluminum plate would be like?

For the motors I plan to use Nema 17 with lead screws like these ones: Pololu - New NEMA 17 stepper motor with optional integrated lead screw
They say the precision can reach 0,04 mm which is good enough for me.

Realize that that spec doesn't include every consideration like backlash. Backlash could be a significant problem for you. I'm not sure because I'm not sure what you are doing with the wax, however if it is for casting excessive backlash will leave defects that show up in the final castings. What I'm trying to say is don't get hung up on precision as there are other factors that make a machine successful.

As for the electronics I was thinking about the TinyG from Synthetos wich connects to the PC through USB since I don't have PC's with parallel ports available. Also this seems a suitable solution for a smaller machine and seems adequate to control the nema 17 motors.

The number of acceptable USB based controllers expands just about every day. You could go in a number of different directions here including Arduino, Beagle Board, Mach with Smooth Stepper and a whole bunch more. I have modest concerns about your motor size but I imagine they would do for any rational amount of wax machining. If not make sure you reserve space for a size 23 upgrade.

Keeping in mind that I'm looking for a bit of precision and I only need to cut soft plastics and wax what do you guys think of this mechanical/electronic combo?

It isn't bad, but I haven't seen many machines of this form factor around machining anything. Being me my tendency would be to build a more conventional machine mainly because that is why I'm familiar with and I suspect they are easier to align for fine precision.

This brings up a question that might help answer your own questions. How does one align the Y axis to the table and the X axis? I just don't see this as an easy thing to do with the otherworld machine. With a moving table, conventional bridge mill design it is far easier in my opinion to align a one off machine. Yes they take up more room. Maybe you have access to a machine shop which probably would do wonders here for making a relatively accurate "otherworld" type machine. If you don't I wonder just how much grief there will be trying to get alignment well under 1/1000" on all travels.

[nalmeida]

Thanks for the extensive and detailed reply, after writing the thread I went to buy a end mill and exchanged some words with the shop owner who has extensive knowledge in cnc machine building and he "convinced" me that the best route was to build an enclosure for the machine I already own and maybe do an upgrade on it. I was excited about the prospect of building a machine but in the end that would take a lot of resources and time.

So I went for plan B, I will build an enclosure and find some sort of vacuum cleaning in order to keep the noise and dust within office acceptable levels.

In any case your remarks were great and confirmed the chosen route. I'll let the professionals do the machines and will stick to use them.

[wizard]

Thanks for the extensive and detailed reply, after writing the thread I went to buy a end mill and exchanged some words with the shop owner who has extensive knowledge in cnc machine building and he "convinced" me that the best route was to build an enclosure for the machine I already own and maybe do an upgrade on it. I was excited about the prospect of building a machine but in the end that would take a lot of resources and time.

It is always good to have somebody to bounce ideas off. The noise and dust are the biggest issues for a true desktop office machine. By the way a really good spindle can go a long ways to keeping a machine quite.

So I went for plan B, I will build an enclosure and find some sort of vacuum cleaning in order to keep the noise and dust within office acceptable levels.

Even if you bought a new machine I suspect you would need an enclosure anyways. Your next trick is to make an enclosure that actually deadens the sound. That can be tricky.

In any case your remarks were great and confirmed the chosen route. I'll let the professionals do the machines and will stick to use them.

Machine building can be a lot of fun if you aren't under the gun to get product off the machine. You do need to pursue it for the right reason though. In any event it looks like you are on the right path, the machine you currently have is rather robust so an enclosure should turn it into a rather useful office machine.