Bridgeport ballscrew retrofit, design the yoke

Hello community,
I would like to upgrade my old bridgeport serie 1 with chinese ball screw and eventually run it with steppers . I don't have a big budget to buy real precision ground ball screw. Chinese ball screw precision should be fine for me since i am actually manual milling with 0.09 in of backlash in the x and y old acme screw. I wish i could fit a 32mm diameter ,5 mm pitch chinese ball screw.

My problem is the design of the yoke. I have no equipement to measure the distance between the two axis. If someone has usefull dimensions, it would really help me. ( a CAD or DWG would be AWSOME!!!)

Thank you guys
i apologize for my newbiness, i have just started this hobby.
a+

Hello, we are manufacturer of ball screws supplying quality and affordable assemblies...we do also offer customization manufacturing and end machining to suit your applications ...kindly send us photo/CAD design and specifications then be able to assist you with your assemblies


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Hey
I'm working on a similar project
I have solid Work files Attachment 310402 of the Yoke

Awesome work!
did you have chance to measure the axis to axis distance ? There is another important design measure to get is the y axis clearance as the nut passes along the z axis bearing housing.
Your yoke look way better than mine, ive just sketch the whole geometry.What ballscrew size are you using ? Are you trying to fit chinese ones ?
Are you willing to share important dimensions or cad ?
thanks a lot , im glad to know some people tryin to do the same type of upgrade!

I don't have a manual Bridgeport but this is interesting none-the-less... I might in the future... keep going fellas and take pictures.

Richard

Attachment 310430

i have just completed the drawing of the x axis , in order to send clear infos the the chinese manufacturer. They quoted me the x and y axis of the bridgeport, 25mm -5mm ball screw ( because i think the 32mm nut won't clear under the way ) and the price is 279 CAD$ !!!! with both screws machined! Even if precision and quality is not best , i think the price justify the try.

Hi

I'm going to use a 32 mm 5mm Pitch screws .
The measurements taken from drawing of a similar Yoke of from HIWIN .
I would be happy to send you the drawing of the Yok .

Note : Yok drawing fits a particular ball screw , it is necessary to adjust it for the screw that you want to use .

Good luck

Yoram

y_shalom did you finished the design of the yoke ? I would really appreciate if you could share some of the measurements.
Thank you

Hello darco30

I rely on this drawing
The most important measure is the distance between the axes (101.6 mm) .
The rest is adapted to the screw you intend to use .

Hope I helped
If you need more help or information. Do not hesitate to contact meAttachment 312208

I decided to make the YOK using a 3D printer (printer also designed and manufactured by me)

(After a note sent to me by e-mail about matching to the machine)

this is the YOK ,,,, full scale from ABS .

I'll check if it fit to the machine .

If necessary. I'll put changes and adjustments.

Then a steel production ..





Attachment 312482

very nice drawing , where did you get it?
thank you for the drawing it will be so useful to me.

As i can see , the yoke bore is 42mm, and the chinese 32mm 5 mm pitch ball nut has 50mm pilot diameter. Thats why i still think the 32mm chinese nut wont fit.. as i said earlier the z axis bearing housing will be in interference with the nut.

nice abs part shalom!

tell me if it fits under the bridgeport.
What year is your bridgeport? If u have noticable wear on the ways , maybe the 101.6mm distance willd be too much , and it will squeeze up the screw. Give me some news. As i will do the same , i am now designing the pulley kit and finishing the screws , as i have a x axis with the old servo type 90 power feed. I will probably need to make a bushing to accomodate the power feed flange needle bearing housing.
See yall

I will try to post some pic as soon as i have more parts.
Ive received my 1600 oz keyed stepper , driver, power supply and breakout board.
I am also tryin to communication with my GS2 (automation direct) VFD to control the spindle via modbus Mach3 ( still having some trouble to communicate , i think i have made a mistake during wiring of my custom rj12 to db9 rs232 adapter )

Quote:

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Originally Posted by daroc30

Attachment 310430

i have just completed the drawing of the x axis , in order to send clear infos the the chinese manufacturer. They quoted me the x and y axis of the bridgeport, 25mm -5mm ball screw ( because i think the 32mm nut won't clear under the way ) and the price is 279 CAD$ !!!! with both screws machined! Even if precision and quality is not best , i think the price justify the try.

---

Awesome! I have a hafco bm-30a or m603d.
I so want to do the same. The diameter is 32mm. Total size is 153cm.

Please dont let this thread die.
Cheers

daroc30, good thread, thanks

Please allow me to provide some of my Manual Bridgeport Ballscrew Upgrade experience..

You can use the standard manual Bridgeport yoke. Just dump the old ACME screw guts out of it and a ballnut for a 25mm screw will fit perfectly.

I ordered my ground screws and ballnut assemblies from Winter Engineering in California. I asked Dave Winter to provide ball nuts with flanges to bolt directly to a standard manual Bridgeport yoke. It fits perfect and my machine runs great.

I spent several months researching the Bridgeport Yoke. I found the same Hiwin yoke print, modeled the part up in Inventor, and ultimately decided the standard Bridgeport yoke was plenty strong. I realized after comparing the Bridgeport Yoke vs the Hiwin Yoke, there was no need to further follow the Hiwin trail.

Also, the Bridgeport Yoke is built whereby all clearance issues are resolved.

Hope this helps,

BT

Hello.
Can somebody upload a 3D design of the yoke ?
(Maybe grabcad or link....)
Thank you!

Have you figured out the Yoke I have 50mm ball nuts and I need a yoke made any help would be appreciated





QUOTE=y_shalom;1850906]Hello darco30

I rely on this drawing
The most important measure is the distance between the axes (101.6 mm) .
The rest is adapted to the screw you intend to use .

Hope I helped
If you need more help or information. Do not hesitate to contact mehttp://www.cnczone.com/forums/attach...d=312208&stc=1[/QUOTE]

Quote:

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Originally Posted by JohnDavis

Hello.
Can somebody upload a 3D design of the yoke ?
(Maybe grabcad or link....)
Thank you!

---

Have you received a 3D model of the yoke?

Quote:

---

Originally Posted by y_shalom

Hi

I'm going to use a 32 mm 5mm Pitch screws .
The measurements taken from drawing of a similar Yoke of from HIWIN .
I would be happy to send you the drawing of the Yok .

Note : Yok drawing fits a particular ball screw , it is necessary to adjust it for the screw that you want to use .

Good luck

Yoram

---

Can you share the Yoke drawing ?

Does anyone know someone who could machine a yoke for me a yoke for me from Fusion 360 Model

Quote:

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Originally Posted by lt00273

Does anyone know someone who could machine a yoke for me a yoke for me from Fusion 360 Model

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Not that I have time... but post up your model and I'll take a look.

It00273 what format is your 360 drawing saved in???

Hi y_shalom, Please can I have a copy of the SolidWorks files.

Quote:

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Originally Posted by WilliamT4450

daroc30, good thread, thanks

Please allow me to provide some of my Manual Bridgeport Ballscrew Upgrade experience..

You can use the standard manual Bridgeport yoke. Just dump the old ACME screw guts out of it and a ballnut for a 25mm screw will fit perfectly.

I ordered my ground screws and ballnut assemblies from Winter Engineering in California. I asked Dave Winter to provide ball nuts with flanges to bolt directly to a standard manual Bridgeport yoke. It fits perfect and my machine runs great.

I spent several months researching the Bridgeport Yoke. I found the same Hiwin yoke print, modeled the part up in Inventor, and ultimately decided the standard Bridgeport yoke was plenty strong. I realized after comparing the Bridgeport Yoke vs the Hiwin Yoke, there was no need to further follow the Hiwin trail.

Also, the Bridgeport Yoke is built whereby all clearance issues are resolved.

Hope this helps,

BT

---

I need your help and advices. I want to install ballnut to my manual Bridgeport that I will convert to CNC milling at low cost.
If I understand from your experience, I need to buy 25 mm ballnut with flanges and ask to drill holes to bolt directly to the standard manual Bridgeport yoke and buy the screws that fit with the 25 mm ballut.

Do you have a draw that shows where to drill the holes in the flanges and how the end of the new screws should be machined?

Thanks,

Jeff

Jeff,

There are internal clearances in the BP Knee Mill that must be observed. For example, the yoke at times runs close to the Z-Axis jack screw. Therefore, material from the Y-Axis ballnut must be removed to provide adequate clearance for it to pass the jack screw.

Similar clearance issues will be found with the X-Axis ballnut. So when you look for screws and flanges, be sure to look for Bridgeport Retrofit nuts and screws. You can confirm the nuts you've selected by comparing with other nuts on the market that are known to fit and provide adequate clearance.

The best documentation on the internet will be found from Hiwin. Hiwin drawings show the cuts necessary for the flanges to pass smoothly inside the knee without interference. Use the Hiwin Yoke drawing with the X and Y drawings to see how the flanges are indexed for the necessary clearance.

These drawings are for 32mm screws, but the clearances are still the same for 25 or 32 mm screws.

I used the BP yoke and 25mm screws on my machine for a while. They worked OK, but I was unhappy with the precision. I installed a Hiwin retrofit kit last year. Very happy with it.

For the Hiwin Manuals
https://www.hiwin.com/downloads.html#manuals

For the Hiwin Yoke
https://www.hiwin.com/pdf/7l0002a3.pdf

For Hiwin Y-Axis Ballscrew
https://www.hiwin.com/pdf/a10jsia1.pdf

For Hiwin X-Axis Ballscrew
https://www.hiwin.com/pdf/a10jsga1.pdf

Quote:

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Originally Posted by WilliamT4450

Jeff,

There are internal clearances in the BP Knee Mill that must be observed. For example, the yoke at times runs close to the Z-Axis jack screw. Therefore, material from the Y-Axis ballnut must be removed to provide adequate clearance for it to pass the jack screw.

Similar clearance issues will be found with the X-Axis ballnut. So when you look for screws and flanges, be sure to look for Bridgeport Retrofit nuts and screws. You can confirm the nuts you've selected by comparing with other nuts on the market that are known to fit and provide adequate clearance.

The best documentation on the internet will be found from Hiwin. Hiwin drawings show the cuts necessary for the flanges to pass smoothly inside the knee without interference. Use the Hiwin Yoke drawing with the X and Y drawings to see how the flanges are indexed for the necessary clearance.

These drawings are for 32mm screws, but the clearances are still the same for 25 or 32 mm screws.

I used the BP yoke and 25mm screws on my machine for a while. They worked OK, but I was unhappy with the precision. I installed a Hiwin retrofit kit last year. Very happy with it.

For the Hiwin Manuals
https://www.hiwin.com/downloads.html#manuals

For the Hiwin Yoke
https://www.hiwin.com/pdf/7l0002a3.pdf

For Hiwin Y-Axis Ballscrew
https://www.hiwin.com/pdf/a10jsia1.pdf

For Hiwin X-Axis Ballscrew
https://www.hiwin.com/pdf/a10jsga1.pdf

---

Thanks for your comments. It does help me.

William, can you explain to me why and how the 25mm screws didn't work as good as the Hiwin retrofit. I understand that the 25 mm screws are smaller compare to the Hiwin retrofit but if both systems have the same backlash on the same BP, the precision should be the same. At least this is what I understood. I really want to convert my BP into CNC at the lower possible cost (I'm cheap). I'm new to this milling machine world, I started last year when I got my manual BP. I like this tool, it makes me happy. If I have to spend more money to get a Hiwin retrofit, maybe I will, but before I order any parts, I need to better understand what I don't understand. Thanks for your help.

Hi Bill,

Really good post but +1 on wanting more information on this. Do you recall any figures on the lack of precision that concerned you? Others on this forum (myself!!) may not have as critical a need for accuracy as yourself it would be useful to put it into context. I can live with 0.5 to 1 thou whereas other chaps need tenths :)

Was it the linear precision that bothered you as I understood this was solvable via software, was it the lack of repeatability perhaps due to the yoke or ballscrew flexing, was it the backlash or something else?

Your posts are much appreciated

Cheers!
David

Hello guys ,
My bridgeport is now running 3 axis cnc with mach 3 free demo software, and i am pretty happy with it, since it is a hobby for me.
x and y axis ballscrew are cheap aliexpress custom made double nut ballscrew 25 mm diam 5 mm lead just like this one https://www.aliexpress.com/item/1pcs...ddresstype=600

The chinese supplier did a very nice job on the shaft tolerances , he reached the dimension to 0.0003in from my drawing dimension. I got both ballscrew completely machined to fit the bridgeport for about 350 $CAD shipping included !!

I made a yoke to fit the chinese nut bolt pattern using the hiwin yoke 2d drawing ( see down the post) I machined a complete solid yoke made of aluminum 6061 t6( enough stiff for what i do with the machine ) The crucial dimension of the yoke is the distance from the two axis to the yoke fixation surface, and the perpendicularity of those axis / surface. I measured my old yoke and added about 0.003 in to the distance in order to compensate for wear( since it is a 1975 BP, and the ways have a little wear on the dovetail).

The third axis is the 6 inches quill, which is not so accurate because of the rack and pinion configuration. It does the job when i have tons of holes to drill. I set Mach3 with backlash compensation , and it is handling it pretty well. I now plan to take the quill motor out and install it using a planetary gear ( ali express chinese nema 34 size!!! ) unit on the knee power screw for better accuracy.

I will try to put down some picture soon.

So for V8kid and jfroux_1 , if you guys have little money to spend on that project i suggest you start with chinese ballscrews. And btw, if you use those dfu2505 ballscrews , the nut flange dont need to be machined since it clears inside the knee.

I hope it helps you

Here is my Yoke for BP, and some other pic from that project







https://www.cnczone.com/forums/attac...d=415376&stc=1https://www.cnczone.com/forums/attac...d=415378&stc=1

Quote:

---

Originally Posted by daroc30

Hello guys ,
My bridgeport is now running 3 axis cnc with mach 3 free demo software, and i am pretty happy with it, since it is a hobby for me.
x and y axis ballscrew are cheap aliexpress custom made double nut ballscrew 25 mm diam 5 mm lead just like this one https://www.aliexpress.com/item/1pcs...ddresstype=600

The chinese supplier did a very nice job on the shaft tolerances , he reached the dimension to 0.0003in from my drawing dimension. I got both ballscrew completely machined to fit the bridgeport for about 350 $CAD shipping included !!

I made a yoke to fit the chinese nut bolt pattern using the hiwin yoke 2d drawing ( see down the post) I machined a complete solid yoke made of aluminum 6061 t6( enough stiff for what i do with the machine ) The crucial dimension of the yoke is the distance from the two axis to the yoke fixation surface, and the perpendicularity of those axis / surface. I measured my old yoke and added about 0.003 in to the distance in order to compensate for wear( since it is a 1975 BP, and the ways have a little wear on the dovetail).

The third axis is the 6 inches quill, which is not so accurate because of the rack and pinion configuration. It does the job when i have tons of holes to drill. I set Mach3 with backlash compensation , and it is handling it pretty well. I now plan to take the quill motor out and install it using a planetary gear ( ali express chinese nema 34 size!!! ) unit on the knee power screw for better accuracy.

I will try to put down some picture soon.

So for V8kid and jfroux_1 , if you guys have little money to spend on that project i suggest you start with chinese ballscrews. And btw, if you use those dfu2505 ballscrews , the nut flange dont need to be machined since it clears inside the knee.

I hope it helps you

---

350 $CAD shipping included !! ??
I’m just a hobbyist, and to tell you the true my Bridgeport is a new tool to me. I really want to convert my BP into a CNC at the lowest cost possible and get a good reliable machine that I’ll use less than 150 hours per year.
Why did you have to build a new yoke? I thought we can just dump the old ACME screw guts out of it and a ballnut for a 25mm screw fit perfectly. I’d like to get the ballnut flange hole drill by the supplier when I’ll order the ballnut flange. I can’t find the pattern needed on the ballnut flange. Do you know where I can find a draw with the pattern needed? I prepared a draw that I want to send to different ballscrew suppliers and I need to add this pattern.
When you use your BP CNC with Mach 3 backlash compensation how happy are you with the results?

Jfroux_1 Exactly, both screws machined in china using my drawings and shipped for 350$ CAD.
I build a new yoke in order to the save the original parts intact.
You will find the bolt pattern in the supplier drawing infos from who you will buy the screws. The orignal yoke has no threaded holes for a ball screw nut.
Mach3 Back lash compensation is working very well for me. Even with the rack and pinion setup on the quill.

Daroc30, the price is impressive! Other than the price, how can you compare the accuracy for the x and y when you compare to a Bridgeport CNC equipped with a Hiwin setup? I’m sure that those cheap china ballscrew do not last very long compare to Hiwin quality, but for a hobbyist that uses this equipment for less than 300 hours per year, is long life a factor?

Quote:

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Originally Posted by jfroux_1

Daroc30, the price is impressive! Other than the price, how can you compare the accuracy for the x and y when you compare to a Bridgeport CNC equipped with a Hiwin setup? I’m sure that those cheap china ballscrew do not last very long compare to Hiwin quality, but for a hobbyist that uses this equipment for less than 300 hours per year, is long life a factor?

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for sure its not the same quality as hiwin, chinese screws are probably rolled screws and hiwin are ground screws. For what i do it is plenty enough , i selected a double nut to increase its axial load capacity hence increasing its life. the long life is not a factor for me , i will probably never change them. And as i said, if a backlash appears in few years, i can extend its life by throwing some backlash compensation and/ or screw mapping into mach3

hi;
in the he link on Ali express only specify 1000 mm as the longest ball screw that can be supplied, these are to small for a bridgeport machine
regards
Mariano

Quote:

---

Originally Posted by daroc30

Hello guys ,
My bridgeport is now running 3 axis cnc with mach 3 free demo software, and i am pretty happy with it, since it is a hobby for me.
x and y axis ballscrew are cheap aliexpress custom made double nut ballscrew 25 mm diam 5 mm lead just like this one https://www.aliexpress.com/item/1pcs...ddresstype=600

The chinese supplier did a very nice job on the shaft tolerances , he reached the dimension to 0.0003in from my drawing dimension. I got both ballscrew completely machined to fit the bridgeport for about 350 $CAD shipping included !!

I made a yoke to fit the chinese nut bolt pattern using the hiwin yoke 2d drawing ( see down the post) I machined a complete solid yoke made of aluminum 6061 t6( enough stiff for what i do with the machine ) The crucial dimension of the yoke is the distance from the two axis to the yoke fixation surface, and the perpendicularity of those axis / surface. I measured my old yoke and added about 0.003 in to the distance in order to compensate for wear( since it is a 1975 BP, and the ways have a little wear on the dovetail).

The third axis is the 6 inches quill, which is not so accurate because of the rack and pinion configuration. It does the job when i have tons of holes to drill. I set Mach3 with backlash compensation , and it is handling it pretty well. I now plan to take the quill motor out and install it using a planetary gear ( ali express chinese nema 34 size!!! ) unit on the knee power screw for better accuracy.

I will try to put down some picture soon.

So for V8kid and jfroux_1 , if you guys have little money to spend on that project i suggest you start with chinese ballscrews. And btw, if you use those dfu2505 ballscrews , the nut flange dont need to be machined since it clears inside the knee.

I hope it helps you

---

I'm rebuilding bridgeport mill, want to know how did the Chinese ballscrew worked out for you in terms of accuracy, is it much big difference as to hiwin's ground ballscrews?

Hiwin's is like $2K for two axis with yoke.

If anyone can provide the accuracy results between the two ballscrews, it would be great.

Thanks.