Bondtech BMG upgrade for the N series

Topics around mechanical design, controller and electronics. Mods & hacks welcome.
dorbar
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Re: Bondtech BMG upgrade for the N series

Postby dorbar » Mon May 29, 2017 6:22 pm

This isn not a big issue but you have to be aware of it! After Installing/asembling the extruder, the easiest way to determin the right direction is loading the filament. If the filament goes in the wrong direction a.k.a not loading at all, than you have to swap those two wires.
I did as per Martin's instructions and the filament went out instead of inside the hotend. So in my case the swaping was not needed in the first place. Again, my printer is from the end of 2016 black motors - if this info is usefull, version wise.
Last edited by dorbar on Mon May 29, 2017 6:57 pm, edited 1 time in total.

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JohnSays
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Re: Bondtech BMG upgrade for the N series

Postby JohnSays » Mon May 29, 2017 6:32 pm

Thank you Martin and JetGuy. I understand that this is all new and I'm sure we will have written in stone understandings as we move forward. I will post my experience once I get and install my dual direct drive.
- John
2 Raise3D N2 Duals, V2 nozzles, Bondtech BMGs, and adjustable table

hardbc
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Re: Bondtech BMG upgrade for the N series

Postby hardbc » Mon May 29, 2017 6:52 pm

I confirm that it's necessary for the silver motors on a dual setup to swap the wires for the left motor.

dorbar
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Re: Bondtech BMG upgrade for the N series

Postby dorbar » Tue May 30, 2017 9:25 am

Please note!!

Please take in consideration that the original heavy-brick-extruder has slightly smaller "horns" than the new BONDTECH!!! As a consequence the extruder carriage MIGHT hit into the rails, because the X-Endstop wasn't triggered.

On this picture you see the Old Raise3D brick and the dimension of interest. The "horns" have different thickness compared to BT's:
Old_Brick.png


On the following picture you can see the situation that MIGHT happen to you too. As every printer is different (sadly) you might not experience this problem. But still be careful and continue reading:
Bumping1.jpg


The last one shows the ...well the misalignment of my printer that prevented me to notice this mishap earlier. When the extruder is in the Top-Left corner, where the X-Endstop is located, the triggering DOES occur. Though there is a tiny, tiny bumping due to inertia. But following the green arrow, you come close to the Home position and here the bumping into the rail-block happens and the X-Endstop DOES NOT trigger.
Bumping2.jpg



THE SOLUTION
- Go back to the old brick... just joking :D (sorry, even as a joke it's a bad idea)
- Try to move, as long as pre-drilled holes permits, the X-Endstop switch toward X+
- Put some duct tape arround the head of the triggering bolt to make it thicker
- Re-align all the rods to pe truly perpendicular but still check the previous solutions
Last edited by dorbar on Wed May 31, 2017 10:45 am, edited 1 time in total.

lami3d
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Location: Marseille - France

Re: Bondtech BMG upgrade for the N series

Postby lami3d » Tue May 30, 2017 9:52 am

Hello Dorbar,

Yes, you have to realign the rods first, i had gave instructions from my experiences to get perfect square with rods viewtopic.php?f=4&t=1613

After, you can slightly move the X limit switch if necessary to get much room by playing with weldings...

i hope you didn't hit the sliding block when the printer was on because it might hurt and bent one of some rods.


And thanks for this advice because there's not a lot of room at that location.
I think i'm going to order one to my N2 and let the N2+ with single bondtech extruder.

I just wanted to know the weight of pancake motor only, to know the weight of this conf with one extruder (even it's not the goal of it) to compare with the one i have. I someone knows that, tx

Jetguy
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Re: Bondtech BMG upgrade for the N series

Postby Jetguy » Tue May 30, 2017 10:28 am

Broken down component weights were in the 5th post.

Broken down individual weight of components:
Stock single extruder aluminum block plus acrylic top plate and 2 thumbscrews without motor is 155 grams
Double aluminum bracket plus acrylic top plate and 3 thumbscrews is 253g.
The stock NEMA17 motor is 288g
Short pancake style 25mm thick NEMA17 153g

The reason I did not specifically show only the weight of the new BMG dual housing (minus motors) is that mine was a prototype and was printed in ABS? by Martin. Shipping version is SLS nylon printed. I don't know that the weight difference matters, but rather than telling you something incorrect, what I can say is compared to the aluminum OEM parts and versions, it's night and day.

Jetguy
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Re: Bondtech BMG upgrade for the N series

Postby Jetguy » Tue May 30, 2017 10:38 am

Same post (5th one down on the first page) I did some math and weighing since I ALSO have the previous Bondtech upgrade.

So basically, compared to a stock setup, right now today if you buy the current version of Bondtech based on the mini and reuse the existing stock NEMA17, you are at 367 grams VS the stock single extruder at 443g
If you swap in the new BMG style, you get dual extrusion direct drive feeders 428g so still lighter than the stock single.
If, you used the new BMG and only installed one motor or they come out with a single motor variant of the BMG bolt on upgrade, that's roughly 428-153=275 grams, and given the normal non configured for an N2 BMG with single 25mm pancake motor is 220 grams, I have to think if they go that route, that's probably closer since my math still left more housing and stuff for a second motor and gears.

dorbar
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Re: Bondtech BMG upgrade for the N series

Postby dorbar » Tue May 30, 2017 11:35 am

@lami3d
Thanks! I'll definitely check your procedure. My Raise3D was already "calibrated" by the local vendor once, but it looks like that moving all that mass on the extruder kicked the things back off-square again.
@jetguy
All that matters to me, is a HUGE overall savings of 400g (+/- 1gr). THIS SHOULD BE THE MOST VALUABLE AND A FIRST TO DO UPGRADE ON THIS PRINTER. I'm a mechanical engineer and I really do know and appreciate what does this weight sawing do to the machine.

lami3d
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Re: Bondtech BMG upgrade for the N series

Postby lami3d » Tue May 30, 2017 2:27 pm

Tx Jetguy for the weight !
I have other questions :
- is the left extruder do the same job (once calibrated with steps) than the mini bontech upgrade (cause i'm very happy with this) ?
- is the right extruder as good as the lefty one ?

Tx for your subjective point of view on this ?

Jetguy
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Re: Bondtech BMG upgrade for the N series

Postby Jetguy » Tue May 30, 2017 2:45 pm

To kind of best explain this, you have to understand what the BMG is the exact same drive gears gripping the filament as the mini you have now, the same filament path and arrangement. So from a shaft to filament grip situation, it's the same parts touching your filament.
What is different, is that rather than the motor directly driving that shaft and hobbed gear we have a 3:1 ratio from motor to the shaft. It allows us use a smaller sized motor that makes less torque, but the tradeoff is the motor can just spin more transforming distance into greater force (law of the lever). The practical printing and extrusion rates of 1.75mm filament are not in any way hindered or limited by the 3:1 ratio or smaller motor. It's the magical sweet spot where the gearing of the motor, the torque and force is much better matched to the speed and feed requirements of our printing.

Since the left and right feeders are carbon copy flips, they work identical.

Basically, the BMG provides even more force than your mini with the bigger stock motor, and yet weighs less (all things considered, Dual VS Single, stock motor VS pancake).
It's based on proven parts and designs (the original mini gear set), competitor based gearset (the 3 to 1 reduction is similar to the E3D Titan) and just a merge of the best of the best capabilities. Again, it provides the same reliable usage and grip and feed path you have now with the mini so it will feel extremely familiar, and yet being lighter, it provided even more force before it would skip a step in a jammed situation.
Last edited by Jetguy on Wed May 31, 2017 11:00 am, edited 1 time in total.

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walshlg
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Re: Bondtech BMG upgrade for the N series

Postby walshlg » Tue May 30, 2017 3:08 pm

FWIW Limit switch arms CAN be gently bent a bit to hit 2-3 mm sooner but they are easy to break. use 2 fine nose pliers

firesped
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Re: Bondtech BMG upgrade for the N series

Postby firesped » Tue May 30, 2017 11:34 pm

fedex came by to drop mine off today, but I wasn't home. I'd go pick it up but I have to work early tonight and i can wait until tomorrow.
RL name: Michael Nolen
printers:
raise3D N2 kickstarter Early Bird
Trinus Deluxe (running smoothieware on Azteeg X5 GT board)
Monoprice Maker Select v2

RogerSt
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Re: Bondtech BMG upgrade for the N series

Postby RogerSt » Wed May 31, 2017 4:38 am

I installed mine yesterday.
The installing video is cool.
After the changes in Simplify3D (M92 415) every thing works.
Raise3D N2 Plus

dorbar
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Re: Bondtech BMG upgrade for the N series

Postby dorbar » Wed May 31, 2017 10:49 am

@RogerST, @firesped
Coiuld you guys confirm the need for wire swapping? Don't forget to mention the type of the motors you had!

THX
Dorjano

Jetguy
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Re: Bondtech BMG upgrade for the N series

Postby Jetguy » Wed May 31, 2017 11:05 am

Also, just a tip I like to do, I use a permanent marker (Sharpie) to draw a line on the motor shaft end. This way, I can better see the motor rotating. I know a minor thing, but might bring a new level of fun and observation to your printing. The OEM extruder with the clear covers, you could see the gear and didn't need this, but with the Bondtech, it can help see when the motor is feeding and how fast. Also fun to see retracts zoom backwards.
Attachments
IMG_0645[1].JPG

RogerSt
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Re: Bondtech BMG upgrade for the N series

Postby RogerSt » Wed May 31, 2017 11:59 am

@dorbar

I dont had to swap cables.
I had the silver color motors (the older one)
I just had to use the right cable for the right motor. (if i switch the connector cables, the motor turn the wrong side)
Raise3D N2 Plus

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woofy
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Re: Bondtech BMG upgrade for the N series

Postby woofy » Wed May 31, 2017 1:29 pm

I fitted my BMG upgrade this morning, excellent instructions an very easy to do. I'm doing a test print now, but its looking good so far.

I had the black motors on my N2+ extruder.
On the BMG I had to swap the motor wires on the rear motor (right extruder) only. The front motor (left extruder) remains unchanged.

Thanks Martin, brilliant job.
Raise3D N2+, Ultimaker2 & UP plus printers.

firesped
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Re: Bondtech BMG upgrade for the N series

Postby firesped » Wed May 31, 2017 1:36 pm

I am doing a wiring swap because

A) I am running SD6128 stepper drivers versus stock. these require inverted direction in the firmware.
B) When I got my original bontech setup a year ago, I pulled one of the stepper wiring motor cables out and I can't find it to put it back in.
RL name: Michael Nolen
printers:
raise3D N2 kickstarter Early Bird
Trinus Deluxe (running smoothieware on Azteeg X5 GT board)
Monoprice Maker Select v2

Jetguy
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Re: Bondtech BMG upgrade for the N series

Postby Jetguy » Wed May 31, 2017 3:47 pm

Just a note here. A user in Europe likely printing with the printer fully enclosed was mentioning the pancake motors were running hot. I just was emailing back and forth with Martin on how I got the numbers (suggested 0.5V Vref) and some details around that.

When we specify a Vref to make it simpler for folks to adjust to, it requires some assumptions. A key one is that you have the stock Raise 3D supplied red A4988 stepper drivers. They should have current sensing resistors (slightly under the heatsink) that say R100 meaning 0.1 Ohms. This is because many different stepper drivers out there look the same, but use different sensing resistors. The point is, those resistors affect how the Vref is related to the actual current setting. So again, when stating a target Vref value, what we really mean is as long as you have the same driver and it has the same sensing resistors, then the calculated vref value will result in the same stepper output current.
Per the A4988 driver sheet, or whatever driver you decide to use in your system, look up the formula.

Point being, the pancake motors are rated at 0.7A, max of 50C ambient temp, and max of 80C temp rise.
Since the motors are intentionally small, they also have very little surface area to distribute any generated heat. Add to this, the SLA printed nylon extruder housing is not an effective heatsink, really nearly an insulator, and so it's imperative the user sets the correct stepper current for driving these motors, as that setting determines how much current and thus power in the motor's coils. If you are running with the covers on the printer, doors closed, and higher temp materials, you might be exceeding the 50C ambient temp. Couple that with a failure to accurately measure and adjust such a tiny voltage (0.5V Vref or less) you would be driving the motor nearer to rated current and that assumes that you have a bit of heatsinking and ambient is controlled below 50C.

Again, what I'm getting at is, per the math and my testing so far, 0.5V Vref exactly, is 0.625A
That means we are running at roughly 89% of rated current if you get that set correctly.
If that overheats to your liking and testing environment, 0.5A is roughly the RMS value of 0.7A.
Basically, a V ref Voltage of between 0.4V (which is 0.5A rating) and 0.5V which is 0.625A, is the target area of operation for this motor.
Less voltage and current is less torque, so that's part of the reason I settled on 0.5V Vref as the suggested instructional value.
Again, I mostly print PLA, always with the top cover off the printer. I do not print ABS due to fumes and leave my smaller printers for parts in nylon and other high temp materials. Just saying, factor that in when making adjustments.


Here is all that math I sent Martin:
Using the A4988 data sheet, we get the formula.
I TripMAX = VREF / ( 8 × RS)

Basically, in shorter terms, RS is the current sensing resistor value and I Tripmax is the current setting of the motor.
8 times the 0.1 Ohm resistor is 0.8.
A simpler way to look at this is 0.8V Vref is = 1 Amp rated current.
In this case, we have 0.5V as the target Vref (based on testing) so that stepper driver current will be 0.5/0.8 = 0.625A
The motor is rated at 0.7A by OMC http://www.omc-stepperonline.com/nema-1 ... p-260.html

Per the extended data sheet, specs on the motor are http://www.omc-stepperonline.com/downlo ... -0704S.pdf
It's saying max ambient is 50C
Max temperature rise is 80C MAX

If you assume that the 0.7 Amp is peak, and they meant RMS, then RMS current would be 0.4950A
That's a pretty easy Vref of 0.4V because that's half of 0.8 making it exactly 0.5A

firesped
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Re: Bondtech BMG upgrade for the N series

Postby firesped » Wed May 31, 2017 6:43 pm

I was posting for something else but lets cover the panucatt SD6128 steppers first.

SD6128 data sheet information

Current limit:
FIG. 1
The current limit can be adjusted by measuring VREF and turning the trimmer (see FIG.1). Connect the + of the voltmeter to VREF and the [-] lead to GND and read the value.
The SD6128 uses a 0.10 ohm current sense resistor so current limit can be computed as follows:
Current Limit = VREF x 2
DO NOT EXCEED YOUR MOTOR’S CURRENT RATING.

actual datasheet is here. http://files.panucatt.com/datasheets/sd ... _guide.pdf

so the SD6128 has the same current sense resistor rating. looking at figure 1 from the data sheet, it actually shows the vref testing point on these are the hole next to the ground and not the adjustment unit. I will need to check to see if they give different values.
RL name: Michael Nolen
printers:
raise3D N2 kickstarter Early Bird
Trinus Deluxe (running smoothieware on Azteeg X5 GT board)
Monoprice Maker Select v2


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