[acannell]

the "standard" spindle speed is 7000 rpm. but dyna says i can upgrade it to 10krpm by buying some pulleys from them.

my question is, can i just turn up the motor speed and get to 10k rpm?

actually, I know I can, because as its configured right now, for 7krpm spindle speed, the motor only runs at about 4000 rpm, due to the pulley ratio.

if i run the motor at 5700 rpm right now, the spindle will be at 10k rpm...

but im assuming there is some reason they dont want the motor running that fast...

does the motor wear out faster or something? the spindle bearings will see the same speed either way, so this has to be all about the motor.

maybe the torque curve drops off really really fast at the upper end of the motor rpm?

but, for my purposes, I want to run the motor faster for using micro-mills, so so i dont thing torque will be an issue.

any other reason?

they say the same belt can be used, and i have determined its a polymax 7M. it could be a 7M545 (7k only) or a 7M560 (7k or 10k). both are the same series, i dont think its a speed rating, its just that the 7M560 is longer to accomodate the larger overall combined pulley circumference in the 10k upgrade.

they want about $400 for the pulley upgrade, which actually seems somewhat reasonable given their usual pricing on things, but i cant afford it, and if i dont need it for micro milling, id rather just turn up the max speed in the parameters!

[acannell]

well the answer to this turns out to be no..you cant just turn the motor speed up..and this is because the DC power supply can only supply about 160V and the motor needs about 190V to run much faster than 4000 rpm...

i tried turning it up and the spindle started bouncing around and lost control. i think the control got confused when the speed wouldnt increase because of the DC power supply limit

dyna says if you can somehow get 190V to the motor then you can turn the speed up..i.e. a different power supply or whatever..

[Fastest1]

Are you running the machine on 120 or 240v?

The output of my Bardac is only limited by my input voltage.

Do you have a lathe? Pulleys are readily available for cheap and usually only need to be bored to your shaft size.

I am not familiar with the 2900, nor have I ever seen one in a picture or in person. How about some pics?

[acannell]

Are you running the machine on 120 or 240v?

The output of my Bardac is only limited by my input voltage.

Do you have a lathe? Pulleys are readily available for cheap and usually only need to be bored to your shaft size.

I am not familiar with the 2900, nor have I ever seen one in a picture or in person. How about some pics?

im running it on 240V..dyna did mention that they need to leave some safety margin in since the spindle amp max voltage is 190V..so running it right at 190V could be an issue if your input power varies and causes it to go up to 200V or something

whats the bardac you speak of? is that a mill?

it would be great to get off the shelf pulleys for it..i should have measured the shaft diameters and stuff when i had it apart..but its pretty easy to take apart. i do have access to a lathe at work so maybe your idea would be best. i suppose i just need to find the right off the shelf pulley.

the DM2900 has a 10" x 7" working envelope and weighs about 1300 lbs..definitely on the mini side of mini mill!

[Fastest1]

The Bardac (mine is a 1600i) is a motor speed controller. Mine has the ability to use 120 or 240 as the input. The drawback is that on 120, the highest output voltage is 140v IIRC. This keeps you from obtaining the max rpm but not a deal killer in my case. The motor runs smooth and fast enough for my needs and can be controlled thru Mach 3.

Your machine is very nice. A toolchanger? Sweet. How many tools? The work envelope sounds small (like Dynas are notorious for) how is that head on the table?

Go to SDPSI for pulleys, MSC and McMaster Carr have them too. Should be simple enough.

Post more pics as you set it up, looks like a nice machine. Pics of the electronics too.

[Fastest1]

Out of curiousity, you say you turned up the spindle speed and it started bouncing. How were you "turning it up"? GCode? The pot on the front of the machine or a pot on an internal speed control board?

[acannell]

The Bardac (mine is a 1600i) is a motor speed controller. Mine has the ability to use 120 or 240 as the input. The drawback is that on 120, the highest output voltage is 140v IIRC. This keeps you from obtaining the max rpm but not a deal killer in my case. The motor runs smooth and fast enough for my needs and can be controlled thru Mach 3.

Your machine is very nice. A toolchanger? Sweet. How many tools? The work envelope sounds small (like Dynas are notorious for) how is that head on the table?

Go to SDPSI for pulleys, MSC and McMaster Carr have them too. Should be simple enough.

Post more pics as you set it up, looks like a nice machine. Pics of the electronics too.

you know i actually do have DC motor speed controller which I might be able to use as a higher voltage power supply for the spindle amp..hrmmmmmmm

the mill really does grow on you..they didnt cut any corners as far as i can tell and its quite capable..the working envelope is 10" x 7". the head is just sitting in the vice to see if i could get it in there at all..im trying to make a toolpath to machine the combustion chamber and then hopefully the ports (with a few angled setups of course), but i need a 3d scanner to do it. it looks like you could actually set the head in there and do some work, but you wouldnt be able to use the tool changer. you could probably get to two combustion chambers before having to slide the head sideways. its got a 6 tool ATC and its really a luxury haha..but even when i run toolpaths with 14 tools its super easy to just pop them out with the button and pop the next one in.

im definitely going to look into the pulleys

[acannell]

Out of curiousity, you say you turned up the spindle speed and it started bouncing. How were you "turning it up"? GCode? The pot on the front of the machine or a pot on an internal speed control board?

i edited the system parameters to allow a higher motor speed, and a higher spindle speed. so then the only thing limiting it was the spindle amp (and DC psupp) ability to actually turn the motor that fast..the spindle got up to maybe 7400 rpm before it just hung at that speed and then started bouncing as the control reacted to things not going as expected

[Fastest1]

The reason I asked was on the Bardac it has a setting which affects the way it hunts for the right rpm. I was worried you had turned that pot on the board.
Dyna didn't take shortcuts. They definitely built great little machines. Of course if you see what they retailed for in their day, you would expect quality.

[acannell]

The reason I asked was on the Bardac it has a setting which affects the way it hunts for the right rpm. I was worried you had turned that pot on the board.
Dyna didn't take shortcuts. They definitely built great little machines. Of course if you see what they retailed for in their day, you would expect quality.

i got the DM2900 for a paltry $2000, and it was near my house..i was definitely in the right place at the right time for that deal


but just a few weeks ago...a DM3000 came on craigslist, RIGHT near where I live...for $2800!! but this time the timing was terrible and i just couldnt grab it...ARGHHHHHHHHHH

[Fastest1]

You got a great deal.

I just saw a DM2000 with what appeared to be the original packing paper on it on CL in Dallas. I wasnt interested due to its size but it looked like it had never been used. ever.

[acannell]

You got a great deal.

I just saw a DM2000 with what appeared to be the original packing paper on it on CL in Dallas. I wasnt interested due to its size but it looked like it had never been used. ever.

ooohhh man...i think imma open a special credit card that remains on standby specifically to purchase dyna mills and lathes

[Fastest1]

Me too for that 2900!