[boss4]

I have a working Series 1 BOSS 4 machine with original steppers, generally in good condition using a Dynomotion KFLOP for control with older Leadshine step drives run from 80V power supply.

I want to retrofit to servo's because I have had some reliability problems with missed steps after 20-30 min of machining. The max reliable speed I can get is also only around 70in/min, I am trying not to spend to much money on the machine as this is strictly for hobby use and won't be making me any money.

So far I have found lots of recommendations for the .75KW DMM servo's but it looks like I would need different pulleys for the 19mm shafts, the shafts are also about 13mm shorter.

If I get the DMM servo's where can I find pulleys?

Also which series of DMM servos are folks using?

If there is a cheaper route I would certainly be interested.

Anyone use the automation technologies nema 34 DC servos I guess with shaft extenders and reduction pulleys?

Again which extenders and which pulleys?

Thanks.

[mactec54]

boss4

The Dmm is the way to go, as for Pulleys, I will post some photo's of what you can do with your original Pulleys, You can also use your power supply with the New Dyn2 Drives, which has a max of 80Vdc input, does your power supply DC output have a filter, the motors to use are there 750w

[boss4]

Thanks for the reply.

The power supply is a Chinese 72v 20 amp toroidal transformer unregulated power supply with I think, 4 10K UF caps. I bought it second hand un-used along with the leadshine drives for a good deal so I am not married to it.

I see there are 2 different .75KW motors the DST and DHT. Are the recommended ones the DST's as sold by CNC 4 PC: 880-DST-A4K1.

Thanks again.

I would love to see pictures.

[Steve_Watkins]

Boss 4 are you using the original cables on your motors? I am rebuilding mine now and I'm concerned that unshielded original cables could be a source for noise and missed steps.

[boss4]

Yes I am, and I do not think thats an issue, I am using shielded control cable between the controller and drives grounded near the drives. Shooting from the hip I would say there is allot more interference from the VFD than from the motor wires.

What happens with mine is It will rapid at 120in/min but I have to set the acceleration terribly low to get the motors up to speed, and back down else it will miss steps on deceleration, and even then I think its close such that after running for .5-1hr in the heat of summer it will loose steps on deceleration when doing rapids. Setting the max speed at 70in/min makes it generally reliable but that is really slow.

If I could do it again I would have either used better, high voltage, drives for the original steppers or just skipped steppers entirely and used servos.

[Steve_Watkins]

I am getting ready to replace the cables on my machine, from the control cabinet to the steppers with shield cable.

From all that I have read the best practice is to use shielded cable from the control cabinet to the steppers and ONLY ground the shield wire at the control box. The shielded cable protects the wires going to the steppers from interference from outside sources, like the VFD, that could lead to missed steps and other weird movements.

[boss4]

I wouldn't be worried about interference between the drives and motors more so about interference generated by the motors, shielding is not a bad thing but I think its un necessary in this case.

I am getting ready to replace the cables on my machine, from the control cabinet to the steppers with shield cable.

From all that I have read the best practice is to use shielded cable from the control cabinet to the steppers and ONLY ground the shield wire at the control box. The shielded cable protects the wires going to the steppers from interference from outside sources, like the VFD, that could lead to missed steps and other weird movements.

[mactec54]

Thanks for the reply.

The power supply is a Chinese 72v 20 amp toroidal transformer unregulated power supply with I think, 4 10K UF caps. I bought it second hand un-used along with the leadshine drives for a good deal so I am not married to it.

I see there are 2 different .75KW motors the DST and DHT. Are the recommended ones the DST's as sold by CNC 4 PC: 880-DST-A4K1.

The DST series motors have a higher performance than the DHT series, both will do the same job, the DST will run faster than the DHT motor, so if you want a little more speed go with the DST motor

It sounds like your Transformer will be ok to use as it is

[mactec54]

boss4

Here are some different ways to do the motor extensions

[boss4]

Those look very nice, which style worked out the best?

I am between lathes at the moment, are any of these available off the shelf or otherwise for purchase?

The only ones I can find clamp on and without the key.

[mactec54]

boss4

The first one is the easiest to make, but takes a little more time, you have to bore some out of the back of the pulley & lick the face, I have another one as well,I need to find the photos, is your Boss 1:1 or 2:1 Pulley ratio

[boss4]

Mine is 1:1, just curious since I've never seen one, does the 2:1 use L series belts? I had considered changing to the 2:1. The Y and Z could be swapped with parts available from McMaster, but how about the X, the driven one looks pressed or threaded onto the ball nut and the housing doesn't look big enough for a larger pulley.

What did you make these out of, 4140?

[mactec54]

boss4

The 2:1 ratio came after the Boss 5 series, the same H belts were used, the material used for the Timing pulley extensions/mounting is 12L14,

The X axes Ball-NutTiming Pulley has a Key & is held in place by the lock-nut,that screws onto the Ball-Nut

14 teeth is as small as you will find with the H series Timing pulleys, If you can make your own Timing Pulley then you can go down to a 13 teeth, It would not be good for the Belt to go any smaller

For a conversion like your machine, 750w motor works, very well at 1:1 on the X & Y axes, the Z axes is were a 2: 1 works better

[mactec54]

boss4

Here is the other Timing Pulley I made, steel & aluminum

[boss4]

So almost a year later I ended up getting 86M-DHT-A6MK1.

I havn't received them yet but it looks like they have 45mm (protrusion from servo) shafts so I think I can use off the shelf timing pulleys if the adapter plates are thin enough.

I am looking at Timing Pulleys H Type?MISUMI?MISUMI USA for x and y and maybe this one:

Timing Pulleys H Type?MISUMI?MISUMI USA

for A.

I believe they will fit. Mactec or anyone else would you mind giving me a second opinion?

If off the shelf pulleys and adapters are available that might greatly increase the usage of these.

[mactec54]

boss4

Yes they may work, as long as they have a boss on the timing pulley that is long enough, mount up one of the motors,to your machine, then you can measure what you will need, you could always add a piece of round material to the boss if it was not long enough, you can also buy just the timing pulley stock, then you can machine them to the length you need

[boss4]

I think the mizuno pulleys worked pretty well. I did have to turn down the boss of the one for the Z axis, though it can be ordered this way. I also added a 3/8in hole into the z axis mount so that I could get at the set screw. It can be ordered with the set screw in the pulley valleys instead of on the boss.

X and Y were perfect as they came with ~3/8" thick nema 34-42 adapters. The pulleys where about 60 dollars each and the boss is about 3/4 inch long so there is plenty of shaft in the pulley (more than an inch).


Attachment 292080
Attachment 292082

[mactec54]

boss4

It looks like your timing pulley choice has worked out fine, you were lucky to get those adaptor plates, did they come from Dmm with the plates

[boss4]

I cut the center bore for the plates on a lathe. Although totally functional they are actually rather crude, the mounting holes are hand drilled. You might recognize one of them as the cast iron mounting plate from the original nema 42 stepper.

I would have used the mill to make them but by that time the z axis drive went bad and the X was loosing steps if I tried to cut anything harder than cheese.

There used to be and maybe still are (but I cant find them) off the shelf nema 34 to 42 adapters.

boss4

It looks like your timing pulley choice has worked out fine, you were lucky to get those adaptor plates, did they come from Dmm with the plates

[mactec54]

boss4

Clear Your PM Box it is full, can't return your question