Upgrading the spindle already! - Myerstown PA USA
 

Hello Everyone,

I'm a violin maker who recently had back surgery. I've been looking for something to help me with the rough carving to enable me to continue making violins. I thought of building a duplicarver but saw a cnc mill and got excited about the idea.

I thought of building one of the 8020 extruded machines but like the idea of this all steel machine. It may be a bit overkill but my wife already has a million projects for me to make with this machine once done.

I am new to cnc so bear with my questions.

Welcome to the forum. Are you sure you do not want to pick a better name to be called by? :)

Bum,

It will be great to see a fine musical instrument made with a MechMate. Good luck with your build.

How large of a machine are you thinking of making?

I'm thinking of a cutting area of 96" x 48" I sometimes make toys and such for kids out of maple plywood. Carriages, Rocking chairs etc. Just cut on my bandsaw and then routed. The cnc would make em in bulk.. :D.

Trust me.. The name Fits.;)

Ok, no disrespect intended, note the :) after the comment.

None Taken.:)

Can anyone tell me how much room I'm going to need to have a 8'x4' cutting surface and have enough room around it to be able to load a sheet of ply into it.? I'm just trying to decide if I can cram it into my shop or if I'll need to put it in the garage.

You load from the ends so you only need enough room on the sides for the size of your tummy! Kidding aside, you need room to be able to walk around the sides. I have just more space at the back where I have some boards stored but the front is how I load large sheets.

Floor footprint of machine will be 10 to 11 feet by 6 to 7 feet. You'll want a 2-3 foot aisle off one end of the machine to facilitate bit changes. Then you have to decide if you're loading from the end (easy, but needs 8+ feet of clearance), or over the rail.

Mine is against a wall the long way, with a 30" aisle at the 0,0 short end, restricted access to the 98",50" end. I have to move the gantry out to 98", load a sheet over the rail, and slide it under the gantry, which is a pain, but it's the only space I have, at least until I use the MM to build a shed for itself. There is another 30" aisle along the long side, and then my cabinet saw, so the two share the aisle as material movement space. Overall, I'm in a 20' x 20' double garage.

I occasionally have to climb onto the table to clamp or access items at the far side. In a perfect world, I'd want 2'+ aisles on both long edges, and an 8' space off one short edge, so total footprint would be 9 feet by 11 feet, with an additional 9 by 9 foot loading area (that could be shared with low height stuff), for a total working envelope of 9 x 20.

Maybe if I design the MM height the same as my cabinet saw outfeed table I can get rid of it and use the MM as my outfeed when using the saw.. Then I'd have a ton of room around it with exception to one short end which would have the saw up against it. But lower the blade on the saw and move the fence off to the side and I would be able to load the MM from that end.

Bum,

Most cabinet saws are higher than what you need for you MM. Do you want to lift a full sheet of MDF or Plywood that high? But that is your choice.

Seems negligible to me as I already rip full sheets on my saw now. So I'm already lifting it that high.

This is exactly what I did... My table surface is 34 inches high... When finished the X rails of my MM will be 33.25". This will allow me to place a 3/4" "table top" across the x rails and form the out feed table for my saw.

Well I have been re-aranging my shop the past couple of weeks and have a spot for the Mechmate now that will allow it to have room around it to work.
I printed out the plans and have been reading as much as I can on this site.
I think I have the mechanical stuff understood and feel confident I can put together a strong reliable machine.
The electronics are going to be my demise though. The more I read, the less sure I am about making the right choices. I'm a hands on learner. I just need to order everything for the kitchen table project and dive in before I even start on anything related to steel.

Bum,

Welcome. Looking forward to your build.

You should do fine. If you get stuck, just post pictures and questions and folks on the Forum will give you a hand.

Bum,
You had chose wisely :)
Start with the kitchen table project go a long way.
Wish you a wonderful building experience.

I opened the flood gates and started ordering parts.. I'm on a tight budget because of being out of work after my back surgery, So I have been racking my brain to find the best "less" expensive solution and reading this forum has become my new job.
I considered building a Wood table but found surplus steel at a good price locally. I went away from the norm on drives and motors which will probably haunt me, but at least I'll learn something from it.
I haven't received any packages yet but I suspect my Parts From Mike will get here first.

Right now I'm staring at the inductance on the motor ratings wondering if the inductance listed is correct.
Wired Bipolar parallel: (600 oz/in)they are rated 7amps,1.82 volts, Resistance .26 and inductance of 1.2..
Series: (600 oz/in) 3.5 amps, 3.7 volts, 1.06 resistance and inductance 4.8
Unipolar (450 oz/in) 5 amps, 2.6 volts, .53 resistance and inductance 1.2

I want to use them Unipolar so I calculated needing 35.05 volts from the inductance rating but read that motors want up to 20 times the rated voltage. 20 x 2.6v 52 volts
I sent an email to the manufacturer asking the power supply requirements of these motors wired unipolar.

Hey Bum,

Is there a reason you aren't sharing the model and manufacturer of these steppers? I'm interested in what you find out.

If you are a bit handy with electronics and can stay below 50 volts (I saw the 56 volts in your post) and 3 amps, you might check-out Anil's DIY Drivers and BOB. He used an Open Circuit design. He seems to have been successful with them. It would also require using Belt Reduction Drives or something like the OM 7.2 Geared drives.

I saw the motors on Ebay for a decent price and Emailed the seller for more information. He doesn't list a model number just a picture of specs. I'm waiting to hear back from him with more info before I order.

I figured it was something like that. Good luck. Hope it works out for you. Let us know.

Have you decided what driver you are going to use? I know that as soon as I got my used motors from Ebay, the first thing I wanted to do was test them with a driver. I happened to have a low tech driver and power supply so I could see them turn. Then I purchase the Gecko's and the PMDX-122 and built my toroidal based power supply before I was sure the used motors were working correctly.

I have Leadshine M880a Drivers, I'm hoping they will work well combined with the pmdx-122 and those motors with 4:1 belt reduction.
I just found a Hoffman enclosure 24"x18"x8" for $35. :)

I'm stressing over the power supply. I want to build one but I'm going to need someone to help me with getting the right transformer. Not to save money but rather the experience of it.

Bum, no worries. Just let us know the voltage and amperage you want - Or let us know your final call on the motors and driver specs - and we'll help you get the parts for the power supply. You'll be surprised how easy it turns out to be.

With Geckodrive stepper drivers, I would use a MAXIMUM of 35VDC for a motor with 1.2mH inductance. Usually I use anywhere from 50% to 85% of the maximum voltage, depending on the top speed that I need. Lower voltage allows the motors to run cooler. Higher voltage allows the motors to run faster.

All of the Oriental Motor stepper motors that I normally use can easily hit 2,500 RPM when run at the maximum voltage, i.e. 32 X SQRT( Inductance); however I can't see the need to run a motor faster than 1,000 RPM on a CNC machine.

If the motor is geared 7.2:1 and uses a 1.5" pinion gear, 1,000 RPM would allow a jog speed of about 10 inches per second. A 1.25" pinion gear would allow a jog speed of about 9" per second. Cut speeds will depend on the material, the cutter and the depth of cut, but on my Shopbot PRT-Alpha machine, I very rarely cut faster than 5 inches per second. Each type of material and each type of cutter seems to have a 'sweet spot' where the quality of cut dictates the speed. Because I don't like to sand, I let the machine show me the best speed.

If you can borrow a Variac transformer, you can easily find the suitable DC voltage for your stepper motors. A Variac is inserted into the AC BEFORE the output transformer. It is used to adjust the AC voltage going TO the transformer. (NEVER use a variac in place of a transformer and NEVER place the variac after the transformer - you'll get smoke.) When I'm checking for optimum settings, I use a 50VAC transformer, which puts out about 70VDC, but with the Variac, I can easily adjust the AC voltage to get any DC voltage that the Gecko can handle. (A Variac goes from 0% to 140% of line voltage.)

The goal is to use the lowest DC voltage that gives you adequate speed. That will give you the coolest motor temperature. Stepper motors quickly lose torque as speed increases, so trying to get excessive speed will require long acceleration ramps which would also lead to problems. Most stepper motors have a low speed range where they run rougher than normal (harmonic jitter). If the acceleration ramp is too long, the motor will stay in that rough area longer than desired.

Telling someone to use 35V when they have PK296A2A-SG7.2 motors and Gecko G203v stepper drivers will assure that they have a tried and tested combination. But, when you use other components, you'll get to go through the process of testing to find what works best for you. Start conservatively (lower voltage) and work towards higher voltages until the motors run too hot. Most motors have insulation that allows them to run at 80C, so they'll be too hot to touch. Personally, I limit my motors to 65C, which is still too hot to handle comfortably, but I don't like the smell of scorched finger tips.

I got an email back from the seller of those Motors I mentioned earlier (modelshopcnc). He recommends a 48v 800 watt supply for 4 of those motors wired Bipolar Parallel with my drives.

I am planning on wiring them Unipolar and before hearing back from him and before hearing From Mike here, I had worked out getting a 36 volt 400va Transformer from Antek model # AN-4218.

Now after hearing from Mike I think I should probably go down to a 24v 300va transformer? If my math is correct this would give me 34vdc. #AN-3212:confused:

Go back and read through the motors threads. We need to talk about the power supply for sure at this point.

Here is a good link. http://www.mechmate.com/forums/showt...83&postcount=1

What parts have you ordered to date if any? If you have not , lets talk about the motors and drives a little bit before you go forward with purchases.

Bum, a minor terminology point: Are you sure you're planning to run Unipolar (6 wire)? Both the Geckos, and the M880A drivers you mentioned are Bipolar (4 wire) drivers, so I think what you mean to be saying is half-coil (which is bipolar, but which uses the same calculations as unipolar, thus the confusion).

I can read these posts a million times but until I get my hands dirty and am forced to find a solution to a problem, None of it is going to sink in. It's just how I learn..

I think you are correct Brad

One of the questions that can't be answered is how your stepper drivers differ from the Geckodrive G203v that many of us use. If you visit the Geckodrive site (http://www.geckodrive.com), you'll find a lot of good basic information about stepper motors. Mariss has published several formulas that will get you started; but, remember that his formulas are tailored to his products. You may find that your stepper driver has slightly different requirements than the Gecko products.

The MechMate community always helps each other as much as possible, but when you have parts that nobody else has used, you become the tester. Some people don't realize that testing new or different products can cost more than buying a tested and proven product. (I have been known to 'blow up' electronics from time to time. Accidents happen and miscalculations can cause instant grief, but that's the price we all pay for doing it ourselves.)

This isn't MM related but was fun to put in. I spent the afternoon making my wife happy by putting a new water heater. So far I'm pretty impressed with this tankless unit.

[IMG]http://i17.photobucket.com/albums/b9...chMate/003.jpg[/IMG]

SumBum, I installed a tankless electric in my house and wished we installed it earlier. Never running out of hot water and not having to heat water you are not using is great.

It looks like you have a Natural Gas Tankless. If you do you might want to check with your local codes on having a copper fuel line. Natural Gas is not corrosive but the sulfur that give the gas its rotten egg smell is. I know steel is a pain to install but if anything was to happen later on and the insurace company finds out you might end up eating the loss.

Either way these things are great and the prices for the units are coming down to almost the cost of a regular water heater. I know it has saved us a lot on electricity.

Hi Russell, Were going from a failing solar hot water system to this. The solar system was very old and corroded and is causing our electric consumption to go up more and more.

I wish I could get natural gas where I live. That soft copper line runs outside to a propane tank.