Power Drawbar for the Bridgeport Mill - Making the Base Plate
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- Опубліковано 20 тра 2023
- I am not quite vertically challenged, but it is a bit of a reach for me to tighten and loosen the drawbar on the Bridgeport mill when I need to change tools. I could have bought a premade power drawbar, but that's not why I got into this hobby. This is the first part in a series of videos of how I made a power drawbar for my mill.
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#bridgeport #millingmachine #drawbar - Наука та технологія
Going to be a great addition!!!
Thank you, and I agree. Probably be the most used accessory in the shop!
Know all about being short too! I use my 3/8 Milwakee bat powered ratchet and has saved my rotor cuff. See you on paart 2 Gregg, you'll love it when done for sure.
I've been using a battery powered drill/driver to do the same. A little more cumbersome, but using a 3/4" wrench sucks.
Great project Greg. At 5'7" I had to stretch and strain on the BP's like that for years and years...Thats why I only have a mill drill and bad shoulders now!
I'm looking forward to getting this complete and working. I'll be able to finish projects faster and I know I won't be dreading tool changes anymore.
Nice work. You had some weird chip action going on there.
It's a learning experience.
I tapped the holes in the pedestal of my mill to 7/8 NC threads. I sent for 3' of all thread and welded nuts on one end of all 4 pieces. The other end I cleaned off the threads and put a blunt point on. I use a digital level to level the table and have no rock even though it is 4 points. The rods dig into the concrete but I don't care. I could have made pucks for under the feet. I can also use them to jack it up enough to get 1-1/2 round bar under for moving it around to the hoist for maintenance.
My only concern with tapping the pedestal of the mill is I don't trust the threads to hold up 2k plus pounds of a mill. Yes, I know that's a ridiculous thing to be worried about. I should just do it. Thanks for the suggestion.
@@MyLilMule gr 2 7/8 bolt is good for 15000 each
@@bheckel1 It's more about the threads in the cast iron base. Not the bolts themselves. Unnecessary paranoia. :)
@@MyLilMule There will be many threads of engagement. My tap just made it through.
3 jaw is inside a thow. er40 backplate showed up early and is now within a tenth. for some reason I don't understand I had to take 5 thow off the jaws on the 3 jaw to get it right. Even though I had it tapped in to under a thow when I started. I had to take 15 off the jaws once. gets rid of bell mouth too. usually that is why I have to do it.
Yours is the second video that I watched today where those brazed carbide boring bars were causing chatter issues. I saw a video a while ago that claimed the the geometry of the cutting edges on those bars was all wrong and they would always rub and chatter. I bought a set of indexable carbide insert type boring bars (a set of 4) and it was like chalk and cheese. You won't regret making the PDB. Tool changes will be a pleasure instead of a chore.
Regards,
Preso
Thanks for the information. Yeah, I just chipped one of the other boring bars while recording for an upcoming video. I was going to get an indexible set, but took the less expensive route. Lesson learned, once again - buy once, cry once.
👍🙂
✌
Not sure what kind of shape your lead screws are in. I've worked on older Bridgeports with a worn lead screw where locking the table in X&Y helped a fair amount with rigidity. Something easy to try anyway, if you hadn't already.
Love the channel BTW. A power drawbar has been on my short list for my Bridgeport, so I was psyched to see the new series starting.
It's in OK shape. Not great, not terrible. Maybe someday I'll replace them.
All the noise you were getting from the boring bar, could have been where you had it up on those tall spacers, no one wants to drill into their table, but maybe shorter spacers closer to the hole your boring might reduce the noise, plus looked like you might be just tad heavy on width you where taking with boring bar, hope ideas help, cool project 👍
All good things to consider. But honestly, I think it's the poor quality boring bars. I need to invest in a green wheel and a diamond wheel for a bench grinder, or get a tool and cutter grinder (I can dream!) and put a better grind on the carbide.
@MyLilMule yeah if not sharp or incorrect angle could cause that
Hi Greg, great refurb. videos, so far I’ve watched the complete Lathe refurb, Bridgeport refurb, and the creation on the mount for the 3 jaw chuck for your Bridgeport rotary table. I have a question from that rotary table one. I noticed you have a newer DRO. I purchased and am refurbishing a 1975 Clausing lathe and then also purchased a 1975 Bridgeport full size knee mill (on the waiting list for refurb…) my mill came with a really old DRO and I would like to upgrade to something better, would you recommend what you currently have? Thanks for your time - Adam in NH.
I like it well enough. But I have only used a few different DROs so I can't say if this one is good enough to recommend. I do have one issue with it, though, and it may be something I have wrong in the settings. Whenever I turn it off, it comes back in SDM mode (vs. Absolute) and it loses it's coordinates. If I were to zero out each axis, turn it off and turn it back on, they wouldn't be at zero anymore. Frustrating. I have to read the manual again to see what I may have done wrong.
I think you might struggle a little with the carbide tooling on your lathe. They really like higher cutting speeds than your lathe appears to be capable of. I'm in the process of ungrading my max 1000rpm lathe to one that will do 3000rpm.
It definitely struggles on harder materials. But 99% of the time, I can get by. It beats grinding HSS tooling every 10 minutes.
Are you sure that's not 4140 or another tool steel?? Sure acts like it. Just wondering!!
It was sold as A36, which I have never had much issue machining before. My guess it's the flame cut edge was super hard.
I believe the boring bars you have for the boring head are ground like garbage. Not sure why but the only person has ever mentioned it was Tony in the boring head video
Probably. A machinist friend suggested a green wheel and a diamond wheel in a bench grinder will help.
@MyLilMule he's right about the boring bar being the problem, it's so far out that it's easy to see the cutting edge isn't on centre in the video.. it looks to be about 0.050 above centre so it's either dragging or it's a really negative geometry depending on how the bar is rotated
Why didn't you bore it in the 13" SBL? The lathe set up tends to be more rigid than the VTM set up in my opinion when boring . Yes there are situations where the VTM can be rigid but this one showed the chatter. Not criticism, only asking why you chose to bore it on a VTM when you have that nice 13" SBL
No particular reason.