Beaver MK.2 retrofit - my first cnc project

[123CNC]

It's alive, it's alive!

Congratulations! The candy store is open and the fun begins.

You may want to try to manually turn your screws through their entire travel to confirm free motion before putting your stepper to the test. This is especially true of the z and possible 'gumming-up' of the spindle if the machine has been sitting around awhile.

Keep up the good work and keep us posted. Its almost as much fun being a spectator, almost.

[jjclear]

Brian,
You're making good progress. Last year I picked up a Lagun mill with the same controller. My intentions were the same as yours. (to update with a PC & Mach software) I decided to plug in the mill and was suprised to find that it worked as is, although with the limitations of an old controller. Since I'm still in the learning stages, the machine will do all that I need. When I start to run into those limits I'll try and follow your steps and upgrade.

J.

[bseibenick]

123CNC, thanks for the tip on checking the screws. The y axis was fine but the x axis needed some attention. I have both the x and y axis turning ok for now but will need more attention later. At this point I had the steppers back on the mill and was actually able to move the table using mach3. The biggest problem I am having is that it appears that the steppers have some kind of internal torque limiter where if the table hangs up even slightly you hear a clicking sound and the stepper keeps spinning internally but doesn't move the table. Does anyone know if this is a common feature of steppers or if it just means my table ways and screws are still too tight?

The other issue I ran into last night was getting the spindle powered. I connected my 220v/3ph power up to the spindle last night and all it does is turn at a very slow rpm rate. I even unhooked the belt from the motor to make sure the head wan't bogging things down but that didn't do it. When I went inside the motor I found 6 wires labled 1,2,3 and 10,11,12. Normally I am used to seeing 9 wires for a 220/440 motor. Because this machine was built in the UK I am wondering if I will have to replace the motor. The motor is marked as 220/440 but it also has a note on it saying delta/wye. From what I have researched there is a type of 6 wire motor that starts on one set of windings and runs on another. Does anyone have any experience running motors like these on straight 220? The motor is a 3hp (2.2kW) from GEC in the UK.

Next up while I am waiting to figure out the spindle issue is the auto lube system. Somehow water ended up in the lines so I am going to flush everything out and put fresh way oil on everything.

Brian

[DennisCNC]

How many volts and amps are you pushing in to the steppers? Sound you hear when the stepper stops spinning but still sounds like it is spinning, the stepper is skipping steps to fix that you need more amps and volts. Another thing about old steppers is they are big but have very low torque, newer steppes half the size will have two or three times the power.

Not are about the spindle motor.

[bseibenick]

Dennis, so that must be why it acts that way the most when I have the acceleration set too high on the axis...basically it is running out of volts/amps. Later today I will try and bump the amps up. I am running the Gecko's at 5A right now so I have 2 more amps I can push through them. From what you said earlier I am guessing the motors want more voltage too as they never even try to get warm. The Gecko's just get slightly warm and I have just a small heat sink on them right now. I figured the 45V from the Bandit's power supply would be enough since that is what the Bandit used to run them. I may have to look at getting a bigger power supply for them.

Thanks for the help.

Brian

[bseibenick]

I tried changing the amps from the Gecko's to the steppers today. The good news is that going from 5 to 6 to 7 amps helped my problem, but I still have issues when trying to drive it faster. The next thing I will look at is raising the voltage. Currently I am using the 45V power supply from the Bandit. I think I will want to try something in the 50 to 60V range. Assuming that most transformers will be good for only one voltage, what would be a good voltage to try to aim for? With the 45V I am currently using the steppers do not even get warm. Would I be getting too greedy for aiming at 60VDC which would require a about a 43VAC transformer? Since I will be driving 3 steppers at roughly 7A each that would be 21ADC. Since the actual amps used should be no greater than 67% that would be 14A. If my math works correctly I would be looking for something in the range of 605VA.

Am I on the right track by going this route?

Also, my steppers are 6 wire steppers currently wired in half-winding or parallel mode. From what I have read this gives the most power. There is not a reason to change to full-winding/series mode is there?

Brian

[bseibenick]

I know it has been a while since my last update. I now have the spindle running thanks to a local motor shop and a VFD. The local motor shop figured out the wiring for the motor and then I purchased a 5hp 1ph input VFD off eBay. Last night I finally had a chance to hook that up and it worked beautifully the first time I powered things on.

I also received parts to build a new power supply for the steppers. I figure that I should be around 55-58VDC to the steppers when I get it done.

The next thing I need to figure out is trying to figure out how to power the z-axis. If the quill was similar to a bridgeport I could put a ballscrew on the front on the quill. Unfortunately this mill has a different design. The only way I can think of adding a ballscrew to the quill is to actually cut a slot in the front of the mill because the quill only protrudes from the bottom of the head by about .5" when retracked. The only other, less accurate, metheod I can think of is to put a pulled in place of the quill feed handle.

Does anyone have any suggestions on how to handle the z-axis feed?

Thanks,
Brian

[bseibenick]

It has been a while since I posted. I had to purchase a VFD to get the spindle to work and I was able to get the mill up and functioning. Using BobCam to generate my gcode I have made some chips. Nothing super exciting other than putting some block text on some aluminum. Until I get the parts to retrofit the z-axis it is a little hard to do much as I have to modify the gcode to include a M01 pause any time I need to change the z-axis height.

I have run into one problem. I have finally found out what model my steppers are. They are a 1.45V 15A stepper. Unfortunately it appears that this is why I have not been able to run them much without the steppers stalling out on me. I am currently using the Geckos but they can only put out ~7A. Would it be easier to try and find some Nema42 steppers that were no more than 7A or would it be easier to get a driver that can handle the 15A? Are there any drivers similar to the Geckos that would support that amperage?

I guess the third option would be to sell all my Nema 42 steppers (I have 4 of these total) along with the Gecko's and purchase servo's and servo Gecko's.

Any opinions would be appreciated...

Thanks for all the help in getting me to this point,
Brian

I will try and get a couple pictures of my first cuts posted soon.

[DennisCNC]

The steppers you have will have little power even if you get a 15 amps to them they are old tech. Buy some newer steppers and you will be set. There is nothing super special about servos other than the fact you have to speed two or three days tunning then and working smooth. Steppers you plug in and go. Here is my BP mill that I finished: BP BTC II Retro

I was messing with limit switched cus there was some noise making then trigger, so I disabled soft limits and was jogging the Z up and hit the travel end and blew up a Viper servo drive so now have to send it to Canada to get another one if that was a stepper drive it would care less if you hit the stop 40 times. Plus you have less fallowing error with steppers. I wish I when with steppers for the mill but the drives and motors came around at good price. I have a 24"x24" router with nema34 steppers on it and it does 430 IPM rapids like nothing and runs perfect!
Go with nice new steppers and you will be a happy miller!

[bseibenick]

Thanks Dennis.

I can get this stepper from Keling for $279 and it is 2830 in/oz.
http://www.kelinginc.net/KL42H2150-42-8A.pdf
The only down side to this stepper is that I believe my lovejoy connectors are only 1/2" dia and this stepper is a 3/4". I would have to open it up on the lathe some.

Or I could get this stepper from Keling for $179 and it is 1810 in/oz.
http://www.kelinginc.net/KL34H2160_62_8A.pdf
This one is a Nema 34 so I would have to make an adapter plate to fit the Nema 42 bolt pattern on my mill.

Either making an adapter or modifying the lovejoy connector do not bother me. Would it be worth the extra $100 per motor ($200 for x&y) to go from 1810 in/oz to 2830 in/oz motors?

Also, looking at their stepper page:
http://www.kelinginc.net/SMotorstock.html
They Keling is showing 8.4V for the Nema 42 and 6.6V for the Nema 34. I built my power supply for the current steppers I have and it is roughly 53-55VDC. Using the typical formula of 20-25 times the stepper rating would give voltages higher than the Gecko can even run at (80V, I believe).

Would I need to change my power supply and potentially go to a different driver or is there another place I should look at for a fairly priced Nema 42 or 34 stepper for my mill?

By the way, the pictures of your BP look great!

Thanks,
Brian

[DennisCNC]

Before the BTC mill I had a smaller Bridgeport and I put ~700oz motors on it with 2:1 reduction and using the old leadscrews it would rapid at 50IPM and had enough power to break 3/8 endmills. So I think the 1810 oz motors will be enough for you and keeping the power supply will work fine, if you need more speed you can always get a different transformer that will make ~75v for the Geckos.
I've been looking around and seems Keling has the best price on the motors.

[bseibenick]

Thanks, I was actually just doing some reading of some comments the guys from Gecko said about the nema 42's having great holding torque but the nema 34's beat them in linearity and speed everytime. It sound like for a little bit of work the nema 34's may be the route to go. Maybe I will even use my existing nema 42 motors to make adapter plates for the nema 34's when I get them!

I guess I will get them on order tomorrow and see what happens!

Thanks,
Brian