series one head drive conversion

[alex 850]

i have a series one boss 5 mill. i want to change the drive system to solid pullys and a electronic varible speed controller. can anyone tell me what size pullys and tensiner and where to order them from.it has the adjustable pullys with the mill now and it is to weak this will be the 3rd rebuild.
thanks alex

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[nate]

Not to be rude, but if its the third rebuild, isint that telling you that you are exceeding the capability of the bridgeports head?

Mabie you should look at upgrading the mill to a more robust unit.

Also, I'm curious what kind of work you are doing that eats the variable speed parts?

[alex 850]

this mill is a weak design from the factory! i am cutting knife parts very simple cuts for this machine. so you have no info to offer correct?
thanks alex

[SCzEngrgGroup]

this mill is a weak design from the factory! i am cutting knife parts very simple cuts for this machine. so you have no info to offer correct?
thanks alex

What Nate was suggesting, quite correctly IMHO, is that it is NOT a "weak" design, which suggests that something *else* is wrong that you have not fixed in the three previous rebuilds. Either you've got some worn part or other problem that is *causing* the premature failures, or you're over-taxing the machine. The basic design is perfectly sound, and quite robust, and what you're experiencing is not normal.

Regards,
Ray L.

[nate]

I wish I did have "info to offer"

I was simply pointing out that if the machine "as built by the factory" is not sufficient, then looking at a different machine may be in order.

That said, i'm all for modifying the machines I own when needed...

[mactec54]

Hi alex 850

nate the variable speed drive is not the greatest in these heads with the plastics bushes
can wear out quite quick

alex it's not that hard to change, what you want to do, the most problem you have is to tension the belt there is almost no ajustment, so you have to add some by sloting the flange of the motor mount,I will post some photos on here you can also see them in my photo gallery

[alex 850]

thank you !i knew thbat i was not crazy! i have replaced those bushing and had good mechanics help with the rebuild .i saw a post here a while back where some body converted theres over because of the noise.
thanks alex

[mactec54]

Hi alex 850

Here are some photos, you won't have to do your head like this, these were special heads I built for some customers, the heads have 5" taken out of the top so it will look different to your head, the motor shaft you can see that has 3.250 off this one I could of taken 1'' more off it but I was going to make some more pulleys for higher speeds, I did do one that runs at 12,000 this one runs at 6,000 so the extra pulleys are 2-1 this one in the photo is 1-1 the belt is a poly-v belt

[alex 850]

the head did throw me off. so you made all of these parts. how much would you charge me to get this setup from you for pulleys and everything else.
thanks alex

[mactec54]

Hi alex 850
I used to build them 5 at a time, but the cost is very high, You can do this yourself, not the same but will work almost as good, I could walk you through it & it should not take very long to do.

The head you see has a disc brake, there is many things that you can't see that were changed, that is why I say you can do it with what you have.
This is a photo of the brake setup

[colin1544]

Hello Mactec I would be most interested to here of your rebuild and any drawings you may have that you would like to share even at a resonable cost to do a 1-1 conversion as My machine sits very close to the ceiling of my workshop and it would help to loose a couple of inches off the height. Cheers Colin

[mactec54]

Hi colin1544

I would be glad to help anyone that wants to do a conversion, this can be simple or very complex, I would suggest the simple, which involves very little change to the machine to do this,

The one in the photos I still have, This was the last one I did just over 10years ago, it still looks as the photos do & runs production 4/ 6 days a week,

In your case were you want to take some out of the top, would take a little more than someone who just wants a straight 1-1, you would only have 4 parts to machine on the head plus the new pulleys if you make them

[colin1544]

Hello
again Mactec the simple one sounds OK does the 4 parts to machine include the brake system, as I like the looks of that, as I finnished up on my machine at the moment just putting a fixed spacer in between the pulleys which works OK but I still get the rattle on the head as I think the origonal varispeed belt is worn in places. So the polyvee belt system looks good as when I used this type of belt on another project some years ago it was alot smoother and quieter spindle. Talking about your brake system do you use one of the origonal pulley sheaves in your mods and does the air brake hold the spindle OK when doing a tool change on the Bristol Erickson quick change toolholder.
Look forward to your coments and any other photos you may have, Cheers Colin

[mactec54]

Hi colin1544

No the disc brake is totally custom, there are no Bridgeport parts in the upper drive area
the low gear also was removed, what machine do you have, a photo of your head would be good.

The brake holdes very well for doing up & undoing the Eichson quick change

I will try & put some more photos with captions this may help for you to see how it was all put together, this will take some time to do

On the motor shaft you should only have a pulley

The front bottom pulley sheave is part of your standard Bridgeport brake, so the simple build will still have to keep this, but it may need to be modifided to lock it on the main spindle shaft, if it can wobble around then it will make noise, the other place noise can come from is in the splines that drive the spindle, but heavy grease can help this

[otpco]

I have a Bridgeport Moog !!! Mach convert . ball screws , servos, etc and am finding the head drive ordinary to say the least . I have replaced the delrin Bushes and key on the motor , belt , ant will now take a look at the other end (quill ) The tool changer is still work in progress .I have air cylinder to replace the Hydrolic thing . I am also looking at the vdf chage to plain pulleys and some sort of speed control .Via the Vdf . any ideas out there would be good someine surely done this before me . Thanks to all lets enjoy this new year and make lotsa mess .

[redford1955]

very impressive mactec54, you do excellent work. i am interested in your conversion for my Bridgeport V2E3 and two Hurco KM3P's. i am looking for more spindle speed to improve the parts i run, aluminum 3D work. i know the easy way would be to update to a newer machining center, but can't fit one in my current shop due to low ceiling. how fast can the spindle be upgraded and still have a continous duty cycle? i have programs that currently run 4 hours with a 3000 rpm spindle speed. do you always eliminate back gear in your conversions? i would love to see more pics and details if you have time.

thank you
keith

[mactec54]

Hi redford1955

The back gear was only removed for the 6,000 to 8,000rpm spindle machines I did do one for 12,000 but this was not worth the extra spindle work needed to get the 4,000 more, doing 3D machining is no problem with 6,000rpm this you have a 2/1 drive pulley set, every thing has to be balanced very well, Bearings have to be high quality right through the head & motor

At 2/1 pulleys the motor is running at 3,000rpm the spindle at 6,000 The stock motor has a rated rpm of 3450rpm

The 2/1 is no good for heavy cutting, you have to change it back to 1/1 for normal milling,

At 1/1 you still can get the 6,000rpm but the VFD is then driving the motor at 120hz I have never run the stock motor at 6,000rpm for more than 30min so I don't know how long they would take the 6,000 rpm for.

[alex 850]

thanks mac. i would like some help please. the simple way for me.
thanks alex

[jacampb2]

Here is a picture of the conversion on mine. I took the simplest approach possible, I think it only cost me about $40. I used sheeves with interchangeable center bushes from surpluscenter.com, and bought the belt from Mcmaster. I used the software on the Gates website to figure out the closest belt/pulley combo that would fit the original centers. My plan was to get the tension perfect with out slotting anything, then use the little bit of extra room allotted by using bushless pulleys to get the belt on and tension it.

It was very, very close, but I had to slot one of the motor mounts by about .375" to get it tight enough to remove slippage. I also kept the factory drum brake, but the rest of my varispeed stuff was completely shelled.

I can try to find the specs on everything if anyone is interested...

Here is the picture:

[mactec54]

jacampb2

This is exactly how it needs to be done

You can use what ever pulleys you want for this as long as you work out the dimenstions so you can get a belt to fit. This is the simplest way to do it, it looks like you have may be 2" above the front pulley before the bearing,

For those who want to lower the top cover this is were you could get 1-1/2" to 2" depending on your pulley clearance on the inside of the cover

You could do this by cutting the top cover down as I did, This was cut on a bandsaw & then machined true to the top bearing housing mount

You will need to redo the 2 Dowel holes as well, this can be done before you cut the cover down or after if you have all the dimenstions/ positions for the holes

The only thing left is to shorten the front shaft by the same amount you cut from the top cover, or you can bore a hole right through the top bearing cover so the shaft can pass through the bearing & cover

The front shaft is case hardened so is a little bit of work to shorten it, the best way is to use a cut off type wheel to do this then you can true it up by facing & chamfer the end in a lathe

As jacampb2 has said you will have to slot the motor mount for some ajustment as well