Boss 8 CNC retrofit and 5 HP upgrade - Build thread

I have a mill thats in good condition with low hours originally servo driven. I will upgrade with MESA cards, Linuxcnc, modern servoes, 5 HP motor and VFD (variable drive removed), and maybe a full enclosure.

My progress thus far is the 5 HP motor is installed and I"m about to fire it up. I also have the Mesa cards and mpg.

PS I will be on the lookout for reasonably priced Kwik Switch 200 tooling. I may even make them from scratch at some point if I feel like doing a little tool post grinding, depends on if I can get what I want without paying inflated prices...

Grab CAD link:
https://grabcad.com/library/bridgepo...-vfd-upgrade-1

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I have a couple Bridgeport Boss mills i am upgrading.. i will follow along !!

what spindle motor are you using, motor RPM's, and pulley ratio ?

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Originally Posted by mongoose

I have a couple Bridgeport Boss mills i am upgrading.. i will follow along !!

what spindle motor are you using, motor RPM's, and pulley ratio ?

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All the data is in the grabcad link for download.
It's a 5 hp baldor vector rated, 6000 rpm max, 1800rpm base speed motor. Its geared down a little bit so not to exceed the spindle speed max of 4200.

i think the spindle will handle more than 4200 upgrade the bearings if necessary

I would not doubt it, however with 4200 as the max speed, I dont have to change any of it, AND I get a full 2 hp over (basically) the entire oem rpm range. If I spin it faster I lose bottom end.
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Originally Posted by dbsharp

All the data is in the grabcad link for download.
It's a 5 hp baldor vector rated, 6000 rpm max, 1800rpm base speed motor. Its geared down a little bit so not to exceed the spindle speed max of 4200.

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The Spindle can run at much higher than 4200 I have run them at 12,000 RPM the main problem at higher speeds is the long splined shaft if it is not perfect which most are not then 6,000 is a safe speed for them to run, the speeds I have done on these machines is at 1:1 and 2:1 direct drive and with no Back Gear in place

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Originally Posted by dbsharp

I would not doubt it, however with 4200 as the max speed, I dont have to change any of it, AND I get a full 2 hp over (basically) the entire oem rpm range. If I spin it faster I lose bottom end.
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At higher speeds you can run smaller cutters which don't need very much torque to run them you can have the best of both high speed and low speed

If you still have the Back Gear in place then 5,000 to 6,000 RPM is max

I have seen your rebuilt drive before and I must say its very slick! Interesting to hear of someone who has run these spindles at this speed. I will still probably not change the pulley ratio or go much above 4200, i'm a bit chicken, lol. This iron is in very nice shape, hardly any wear as far as I can tell, so my goal here is to make a setup that will last for a long time. It seems like most spindles with quality bearings like this should do 6k just fine with quality grease, above that ceramic seems to be the way to go, and above the 8k range, I think you pretty much need an oil air mist for long term dependability. At least this is what I have gleamed from reading and listening from folks a lot smarter than me.

PS any recommendations on a quality 750w servo that can get splashed with coolant?

Well I got it running today. Runs great and rpm is dead on. Just one problem, there is a slapping or grinding noise coming from the spindle. At low speed (200 rpm) in high gear, it makes a knocking sound exactly once per spindle revolution. At higher speeds its sounds more like grinding with more than one noise per revolution. When the quill goes 3/4 of the way down or more, the noise seems to disappear. In low gear the noise is not as distinct as in high gear. I think I need to check out the spline drive and bull gear. I fear that the spline or bull gear shaft is worn in the area it was most used. The ways, ballscrew backlash, and quill on this machine look amazing and fresh so I'm hoping to find another source for noise. I did have to replace the bearings for the belt pulley, they felt trashy, so maybe I'll get lucky and find another cheap part that needs replacement.

I'm hoping I don't need to replace the spindle or anything. I'm not sure if these would even be the same as a normal bridegport parts.

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Originally Posted by dbsharp

I have seen your rebuilt drive before and I must say its very slick! Interesting to hear of someone who has run these spindles at this speed. I will still probably not change the pulley ratio or go much above 4200, i'm a bit chicken, lol. This iron is in very nice shape, hardly any wear as far as I can tell, so my goal here is to make a setup that will last for a long time. It seems like most spindles with quality bearings like this should do 6k just fine with quality grease, above that ceramic seems to be the way to go, and above the 8k range, I think you pretty much need an oil air mist for long term dependability. At least this is what I have gleamed from reading and listening from folks a lot smarter than me.

PS any recommendations on a quality 750w servo that can get splashed with coolant?

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Grease is the limiting factor for spindle speed but up to 12,000 RPM is normally not a problem most high speed spindles 24,000 RPM plus are all using Grease filed Bearings

mactec, I have read there is a world of difference in the type of bearing and preload between a heavy duty milling spindle and a high speed light duty/ router spindle. This seems to be why they can get away with the speeds where the milling spindles cant. though as with many things the extra speed probably just shortens the life but will work for some time.

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Originally Posted by dbsharp

mactec, I have read there is a world of difference in the type of bearing and preload between a heavy duty milling spindle and a high speed light duty/ router spindle. This seems to be why they can get away with the speeds where the milling spindles cant. though as with many things the extra speed probably just shortens the life but will work for some time.

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No difference in the Bearings or the preload, the configuration and spindle design is different, yes the high speed spindles can have a shorter life depending on how they are used

So just the Bearing arrangement and spindle design that is different

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Originally Posted by dbsharp

Well I got it running today. Runs great and rpm is dead on. Just one problem, there is a slapping or grinding noise coming from the spindle. At low speed (200 rpm) in high gear, it makes a knocking sound exactly once per spindle revolution. At higher speeds its sounds more like grinding with more than one noise per revolution. When the quill goes 3/4 of the way down or more, the noise seems to disappear. In low gear the noise is not as distinct as in high gear. I think I need to check out the spline drive and bull gear. I fear that the spline or bull gear shaft is worn in the area it was most used. The ways, ballscrew backlash, and quill on this machine look amazing and fresh so I'm hoping to find another source for noise. I did have to replace the bearings for the belt pulley, they felt trashy, so maybe I'll get lucky and find another cheap part that needs replacement.

I'm hoping I don't need to replace the spindle or anything. I'm not sure if these would even be the same as a normal bridegport parts.

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Just needed a little alignment to get the clutch dogs lined up. Now it sounds much better.

I rebuild the kwik switch nut too, it's a little sticky I'm thinking the roll pin might be oriented so the edges are digging into the nut. Might just need breaking in, I'll take it apart again and check.

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Originally Posted by dbsharp

Just needed a little alignment to get the clutch dogs lined up. Now it sounds much better.

I rebuild the kwik switch nut too, it's a little sticky I'm thinking the roll pin might be oriented so the edges are digging into the nut. Might just need breaking in, I'll take it apart again and check.

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No the Boss CNC machines have a different Spindle, the spline area is much longer than a regular Bridgeport manual mill, depending on what head you have most of the other parts are the same

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Originally Posted by mactec54

No the Boss CNC machines have a different Spindle, the spline area is much longer than a regular Bridgeport manual mill, depending on what head you have most of the other parts are the same

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The splines looked new and were very tight. Pulling apart the cabinet, I found the hour meter and it has not moved off 0 yet. I'm thinking this mill's story of being a community college mill turned on a few times a semester might be true.

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Originally Posted by dbsharp

The splines looked new and were very tight. Pulling apart the cabinet, I found the hour meter and it has not moved off 0 yet. I'm thinking this mill's story of being a community college mill turned on a few times a semester might be true.

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That's will be a good machine then almost all machines from community collages are used very little, mainly because a machine like what you have is a challenge for some teachers with little to no experience with machines like this

Got some more progress now. Now I'm looking at getting the enclosure designed. I'm also looking at how to better protect the ways. I'm kinda surprised the simple rubber flap is the best anyone has done. I was thinking of metal covers on the y axis right in front of the user, I kinda doubt it would fit on the other side of the y axis, rubber flap might be the best there.
I'm thinking of having a chip tray that slides outside the bottom of the enclosure. I'd like to add more rubber flaps to the knee so chips go into a pan not under the knee.

DB, looking good ! i know what you are saying about those rubber covers, but all the boss' i have run into over the years have exceptional ways.. so they must work ! Im hoping to build an enclosure around the table itself so it will contain the chips there... guess we will see..

here is a picture of my way bellows on my heidenhain BP ... mind you the ways are smaller than on the boss if you find something like that LMK and ill be buying them as well !!!

Joe

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Originally Posted by mongoose

DB, looking good ! i know what you are saying about those rubber covers, but all the boss' i have run into over the years have exceptional ways.. so they must work ! Im hoping to build an enclosure around the table itself so it will contain the chips there... guess we will see..

here is a picture of my way bellows on my heidenhain BP ... mind you the ways are smaller than on the boss if you find something like that LMK and ill be buying them as well !!!

Joe

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I have the OEM table chip guards for the boss. Still some chips would fly over it and out the backside I think. And any coolant would soak the floor.
Maybe you would be interested?

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Originally Posted by dbsharp

I have the OEM table chip guards for the boss. Still some chips would fly over it and out the backside I think. And any coolant would soak the floor.
Maybe you would be interested?

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post up some pics.. maybe !