Pneumatic Power Drawbar for Bridgeport Mill

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Dec 14, 2017, 02:41 PM
thehomeengineer

4 Attachment(s)

UPDATED Pneumatic Power Drawbar for Bridgeport Mill UPDATED

After falling ill, I was struggling to change the tooling on my Bridgeport mill so decided to build a pneumatic power draw-bar. There are plenty of great videos on You Tube and other sites for research, So I decided to try and incorporate all the bits I liked in to this project. This works very well and makes tool changing a lot simpler. Some of the hardware was purchased from eBay air fittings, air hose, cylinder linear bearings and shafts, springs, approximate cost for items £50.00 the rest was manufactured in the workshop.
http://www.modelengineeringworkshop....s/IMG_0736.JPG

UPDATE
After using power-draw for a few years it occasionally would play up and lift the back-gear lever and jam. I removed it this weekend as I had just had enough with the jamming issue. (doesn't help when you are not well and patients are a bit short) However after 20 minutes of having to manually change the tooling it was definitely the next urgent job to sort and sooner than later. So I have now fixed the power-draw bar directly to the top aluminium casting via three steel stand offs and an aluminium plate machined to suit. This still allows the back-gear and brake lever to operate without any interference from the modification.

Anyone considering building a power draw-bar please don't make the same mistake I made and bolt direct to top casting and not the back-gear castings. As per 1st photo.

The pillars/stand offs are 36mm high and 120 degrees apart on a 136mm Pitch circle diameter (PCD). The first pillar (datum point) is placed equally (by eye :rolleyes:) between the brake and back-gear lever. This allows the other pillars to miss nuts etc on the casting top. I used M6 threaded studding, screwed and loctited into the pillars to fit the aluminium top casting and M6 cap screws, plain washer and spring washer to lock the aluminium flange to pillars.

Attachment 31930 Attachment 31931 Attachment 31932 Attachment 31933

Good luck in your power draw-bar build. One of the best modification I have ever-made. So much easier for tool changing and so quick.
The Home Engineer
Dec 15, 2017, 12:49 AM
extropic

Is the driver an air impact or an air ratchet?

Do you have a pneumatic schematic to share?

I'm guessing that the cylinder engages the socket with the drawbar and the springs disengage them.

Are both the driver and the cylinder controlled by the same switch? I'm wondering about the timing of powering the driver before engaging the socket onto the drawbar (or is it a non-problem)? Or, are there separate switches for cylinder and driver?

Real nice looking setup.
Dec 15, 2017, 11:54 AM
thehomeengineer

3 Attachment(s)

Hi
it is a butterfly impact driver and both the cylinder and driver are driven from one switch (The exsisting butterfly switch was removed from the top and modified).

Attachment 20919 Attachment 20920 Attachment 20921

There is no timing the impact driver socket engages over the drawbar with no problems. I will have to draw out the the pneumatic set up and post, but for futher photos are on my web page. http://www.modelengineeringworkshop....er-drawbar.php
Dec 15, 2017, 01:46 PM
extropic

Thank you again. I understand the controls now.

In the pics, on your web site, I see a generous chamfer that you added to the top of the drawbar hex which may facilitate the socket engagement while the driver starting.

Your work is a pleasure to see. Keep posting and you'll fit right in with the best I've seen on this site.

PS: looking at the pics regarding "Bridgeport Mill VFD and Tachometer" I see some interesting clamps being used on the drill press. I don't think I've seen that type before. Are they another creation of yours?
Dec 16, 2017, 12:37 AM
DIYer


Thanks thehomeengineer! We've added your Pneumatic Drawbar to our Machining category,
as well as to your builder page: thehomeengineer's Homemade Tools. Your receipt:

<div id="blocks"> <div class="block b1 pngfix"> <div class="bimg"> <div> <a href="http://www.homemadetools.net/homemade-pneumatic-drawbar"> <img src="/uploads/207933/homemade-pneumatic-drawbar.jpeg"/> </a> </div> </div> <div class="head pngfix"></div> <div class="left pngfix"></div> <div class="right pngfix"></div> <div class="blockover b1 pngfix"> <div class="title"> <a href="http://www.homemadetools.net/homemade-pneumatic-drawbar">Pneumatic Drawbar</a> <span> by <a href="http://www.homemadetools.net/builder/thehomeengineer">thehomeengineer</a></span> </div> <div class="tags">tags: <a href='http://www.homemadetools.net/tag/pneumatic'>pneumatic</a>, <a href='http://www.homemadetools.net/tag/drawbar'>drawbar</a> </div> </div> </div> </div>
Jan 10, 2018, 02:08 AM
thehomeengineer

Hi extropic
Thank for the kind words and sorry for the delay in responding
I made the clamps and now have about 10 sets of them if not more. I made my first one when I did my apprenticeship project some 34 years ago. The are very quick and useful to use, so decided to make a batch of them for the workshop. I will do another post on homemadetools.net for the clamps, as you are not the first person to ask about them.
Thank you again for viewing my posts
The home engineer
May 17, 2018, 02:18 PM
Saltfever

Sorry I am late to this party by about 4 months. I couldn't see the clamps clearly in your link mentioned above. Did you subsequently post a clamp-specific thread yet?
May 18, 2018, 02:21 AM
thehomeengineer

Quote:

Originally Posted by Saltfever

Sorry I am late to this party by about 4 months. I couldn't see the clamps clearly in your link mentioned above. Did you subsequently post a clamp-specific thread yet?

Thank you for your interest here is the link http://www.homemadetools.net/forum/c...p-system-65679
The Home Engineer
May 18, 2018, 04:52 PM
Saltfever

Very Nice. THANK YOU. :-)
Nov 7, 2019, 01:14 PM
thehomeengineer

Hi All
I have updated this old post today after modifying the way the power draw-bar attaches to the machine. So if building a power-draw bar don't make the same mistake I made.
The Home Engineer
May 5, 2021, 10:19 AM
tmate3

When you drilled and tapped the aluminum casting, how did you keep the resulting chips and debris from falling into the head?
May 5, 2021, 03:12 PM
thehomeengineer

Quote:

Originally Posted by tmate3

When you drilled and tapped the aluminum casting, how did you keep the resulting chips and debris from falling into the head?

Hi
I also fitted a digital tachometer and this was set up on the back gear in the head. This then ensures the speed is correct in both high and low ranges. So the head was stripped down for this and the aluminium casting drilled off the machine. It also was a good time to change the two belts as it was all apart.
hope this answers your question
The Home Engineer