Bridgeport Series 1 MDI Conversion

**Chaz** · 03-01-2019

Acorn control board and MPG ordered yesterday, so getting ready to start retrofitting.

I managed to get a quote from DMM. Great company, quick response.

They have a Nema 42 replacement motor (fairly new, released a few weeks ago). My motors (According to them) are Nema 42.

The ones they are proposing are same shaft size which is very helpful (5/8th inch) as I am struggling to find direct replacement pulleys with 12 and 13 teeth respectively (14 is minimum generally).

The issue is the motors are not a perfect fit (mounting holes are a bit different - 75 PCD vs 82 PCD, probably minimal effort to sort this but they are fairly pricy and potential import tax from Canada. These are 1.3 KW servos, running off 220V (so high volt feed). Including 3 meter encoder and motor cables plus the Acorn DB 25 cable and programming lead, these work out at around £500 ish per axes.

I know the stuff from BST Automation and other sources listed are cheaper. Id like to have as little mechanical fuss / changes to make this all work (most seem to have 19mm pulleys), so modifications will be necessary but it looks like exact like for like change, so mods will have to be done anyways.

Thoughts?

**m_c** · 03-01-2019

DMM sales are always very quick to respond.
Their tech support, not so quick. There have a been a couple guys using KFlops that have had issues. One just couldn't get a drive to tune in analogue mode until he fitted their suggested mains filter, yet all the other drives were fine without the filter, and the issue moved with the drive, not the wiring.
Somebody else blew a drive up within seconds of turning it on, which was apparently due to being over-voltage, and due to them not fitting the recommended mains filter they wouldn't warranty it, yet the other drives never failed.
Plus they use capacitive encoders.

Their big advantage as you've discovered is they've specced the motors so they're far more likely to be a drop in replacement for old stepper motor systems.

Personally if cost was the main concern, I'd opt for cheap Chinese.
What tooth profile are the pulleys?

**Chaz** · 03-01-2019

Originally Posted by m_c

DMM sales are always very quick to respond.
Their tech support, not so quick. There have a been a couple guys using KFlops that have had issues. One just couldn't get a drive to tune in analogue mode until he fitted their suggested mains filter, yet all the other drives were fine without the filter, and the issue moved with the drive, not the wiring.
Somebody else blew a drive up within seconds of turning it on, which was apparently due to being over-voltage, and due to them not fitting the recommended mains filter they wouldn't warranty it, yet the other drives never failed.
Plus they use capacitive encoders.

Their big advantage as you've discovered is they've specced the motors so they're far more likely to be a drop in replacement for old stepper motor systems.

Personally if cost was the main concern, I'd opt for cheap Chinese.
What tooth profile are the pulleys?

Hi,

The pulleys are 12 (X and Y) and 13 (Z) respectively. H pitch. Beltingonline are telling me they can have them made to order but warned that they will be pricy (I need to send them some pics) as I've suggested that maybe I just bore them out and install a grubscrew.

In terms of costs, sure, I dont want to spend more money than I need but I could get this machine running on steppers for a lot less money, that's not the point here.

If the DMM stuff isnt much better or doesnt offer more than perhaps an easier fitment, then I might as well save the money and use that for a better touchscreen / PC whatever. I'm not trying to cheap out on the build but dont see value in paying for something that doesnt offer better. Of course the law of diminishing returns persists too.

As an example I have Panasonic drives and motors on Thor and cheaper Chinese stuff on my old Triac. The Triac worked OK but no doubt the Panasonic stuff is better. The only reason I bought them was that I got some stuff at good prices from an Ebay seller. I wont pay RRP or similar for Panasonic.

I can get away with a 750W system, been avoiding it due to mounting concerns, bracketry might be OK, motor shaft diameter and length are the main concerns. One guy on Youtube has basically extended his motor shafts to suit.

**Gary** · 03-01-2019

I bought some bar stock and made them myself. not that hard.
Or modify the existing pulleys to fit on the new motors.

Originally Posted by Chaz

Hi,

The pulleys are 12 (X and Y) and 13 (Z) respectively. H pitch. Beltingonline are telling me they can have them made to order but warned that they will be pricy (I need to send them some pics) as I've suggested that maybe I just bore them out and install a grubscrew.

In terms of costs, sure, I dont want to spend more money than I need but I could get this machine running on steppers for a lot less money, that's not the point here.

If the DMM stuff isnt much better or doesnt offer more than perhaps an easier fitment, then I might as well save the money and use that for a better touchscreen / PC whatever. I'm not trying to cheap out on the build but dont see value in paying for something that doesnt offer better. Of course the law of diminishing returns persists too.

As an example I have Panasonic drives and motors on Thor and cheaper Chinese stuff on my old Triac. The Triac worked OK but no doubt the Panasonic stuff is better. The only reason I bought them was that I got some stuff at good prices from an Ebay seller. I wont pay RRP or similar for Panasonic.

I can get away with a 750W system, been avoiding it due to mounting concerns, bracketry might be OK, motor shaft diameter and length are the main concerns. One guy on Youtube has basically extended his motor shafts to suit.

**swarf-boy** · 04-01-2019

Just been checking out your acorn control.
Interesting unit. Quite a lot in the Kit.

Options seem to get strangely pricey though
( $45 for a dual circuit E-stop, being a stand out).

See those 4 series drives look to have built in S curve feature.
Didn't know that was a feature in drives. ( every day is a school day, as they say).

**Chaz** · 04-01-2019

Originally Posted by swarf-boy

Just been checking out your acorn control.
Interesting unit. Quite a lot in the Kit.

Options seem to get strangely pricey though
( $45 for a dual circuit E-stop, being a stand out).

See those 4 series drives look to have built in S curve feature.
Didn't know that was a feature in drives. ( every day is a school day, as they say).

Yep, mine was ordered on Wednesday, import tax is a bit harsh, might be delivered today or Monday latest.

I have some potential Panasonic servo motors sorted, will check over the weekend and see if they will work then i need to sort out mounting / pulleys.

**Chaz** · 06-01-2019

I'm trying to decide what motor to go for.

80 Size - 19mm shaft but 35mm long.
90 Size - 16mm shaft, same length.

Both those have near identical specs.

110 Size is almost a direct replacement but the shaft is 19mm and longer which is I think is ideal. This is for a 1.5 KW setup, around $100 per setup more expensive (not much of a concern).

Which would you go for?