vulcan bomber Posted March 6, 2012 Share Posted March 6, 2012 Thats not right imho. Our bridgeports and the 2 cheapo chinese coppies at work and the 6 milling machines we had at college all had the draw bar sticking well out the top, we tighten them with a ring spanner. Sure you've got the quill right up? Quote Link to comment Share on other sites More sharing options...
ejparrott Posted March 7, 2012 Share Posted March 7, 2012 ^what he said^ My clone has a 1/4" thick washer, nothing more, and the hex is a good inch above the top of the spindle. I'd use a socket anyway, attached to a quality air wrench - give yourself a cheap power drawbar! Quote Link to comment Share on other sites More sharing options...
LandyManLuke Posted March 7, 2012 Author Share Posted March 7, 2012 The quill is right up, no issue there. I'll maybe take some photos tonight. The hex sits down inside the shaft, against a shoulder, if there were a washer to stop it dropping down in to the shaft, that'd probably sort the length issue too. I'll either find a suitable washer, or a length of tube to fill the gap between the hex and the top of the spindle. Power draw bar is definitely the future. Quote Link to comment Share on other sites More sharing options...
ejparrott Posted March 7, 2012 Share Posted March 7, 2012 Our new XYZ has a 'proper' power drawbar, and its proving to be a bit of a pain...go with a decent air ratchet if you have compressed air in your workshop, and just use a normal 6-side socket. You have another tool for working on the landy too... The XYZ drawbar is currently removed, and the operator is back to using his 19mm spanner..... Quote Link to comment Share on other sites More sharing options...
LandyManLuke Posted March 7, 2012 Author Share Posted March 7, 2012 Already have air piped round the workshop, and a few air ratchets/drivers, so no issues there. A few youtube videos show a butterfly valve impact wrench permanently mounted above the spindle, which seems like a good idea. Quote Link to comment Share on other sites More sharing options...
mickeyw Posted March 7, 2012 Share Posted March 7, 2012 Not sure why you would need to graft/use an air wrench onto the drawbar. If the threads concerned are all clean, you should be able to spin the drawbar in your fingers most of the way, then just nip up with a ring spanner for the last l'il bit, probably no more than 1/2 a turn. Doesn't need to be tightened by a gorilla, that's what knackers drawbars and chucks Quote Link to comment Share on other sites More sharing options...
simonr Posted March 7, 2012 Share Posted March 7, 2012 The point is just make it easy and quick. This is particularly so if you want to add your own auto tool changer. The same could be said of an electric knee lift on a mill - or a forklift truck for that matter. It's not about tightening it more (you reduce the air pressure to something sensible). Si Quote Link to comment Share on other sites More sharing options...
ejparrott Posted March 7, 2012 Share Posted March 7, 2012 The point is just make it easy and quick. It's not about tightening it more (you reduce the air pressure to something sensible). Si Yes, I wasn't advocating doing the drawbar tighter. We use a 1/2" drive air ratchet on our BT50 spindle butler elgamill, for convienice and 'constant' tightness on the drawbar (which I made ), and I can hang on a spanner far more than it can. It just makes life easier. Quote Link to comment Share on other sites More sharing options...
longlandy Posted March 7, 2012 Share Posted March 7, 2012 Is yours a vari speed head, mine is and the draw bar head sits down, but hey why I do I bother posting, what ever I say is contradicted so god knows how Ive stayed in business twenty years!! Quote Link to comment Share on other sites More sharing options...
simonr Posted March 7, 2012 Share Posted March 7, 2012 Is yours a vari speed head, mine is and the draw bar head sits down, but hey why I do I bother posting, what ever I say is contradicted so god knows how Ive stayed in business twenty years!! I wouldn't take it personally. You and everyone else just answers based on their own experience. It is possible that you are both right. From my point of view, since drawbars for different Bridgeport clones are different lengths, it is perfectly possible that the bar in a given machine was not original or not originally for that machine. Both my Bridgeport's, one CNC and one Manual have had quick change tool holders so no draw bar at all! Quote Link to comment Share on other sites More sharing options...
longlandy Posted March 7, 2012 Share Posted March 7, 2012 The bridgeport is my only machine with a draw bar as its my only manual machine and even that seems like one too many, power is the way forward . I did try fadal vmcs back in the late 90s and they had the most unreliable power drawbar ever made, I felt like retro fitting manual to them! Quote Link to comment Share on other sites More sharing options...
vulcan bomber Posted March 7, 2012 Share Posted March 7, 2012 The bridgeport is my only machine with a draw bar as its my only manual machine and even that seems like one too many, power is the way forward . I did try fadal vmcs back in the late 90s and they had the most unreliable power drawbar ever made, I felt like retro fitting manual to them! My opinion is that for someone messing about in the garage, a powered draw bar isnt required, in industry maybe it is because at the end of the day, time is money. Also i'm not saying what your sayig is wrong, but i will point out that as i've said above.. We're messing about in a garage not making racing car parts in a sub contract machine shop like i do day in, day out. Quote Link to comment Share on other sites More sharing options...
LandyManLuke Posted March 8, 2012 Author Share Posted March 8, 2012 Thanks for all the useful replies again. It's not a vari-speed head, it's the standard head with 2-speed motor (u/s, being replaced with something different) and stepped pulleys. I agree that the full productivity of a power drawbar won't be seen in my garage, but if/when I get round to it, it'll still be a fun project to make one myself, and it will make tool changes easier. At the moment, the priority is to get the spindle turning to check that the bearings aren't grumbling etc at speed. The slideways look ok, the screws are ok, if a little worn, but that doesn't really matter as the original Heidenhain DRO still works (once it's warmed up), so for the first few manual bits at least, they'll be ok. I've already stripped and fixed the fine feed mechanism and quill return spring, which weren't working, and the quill auto-feed disengaging mechanism had been jammed, but a strip down and clean sorted that. The trigger pin is worn though, so I won't be using the auto stop! Luke Quote Link to comment Share on other sites More sharing options...
simonr Posted March 8, 2012 Share Posted March 8, 2012 Can we help at all in getting the spindle running? What's the problem? Si Quote Link to comment Share on other sites More sharing options...
LandyManLuke Posted March 8, 2012 Author Share Posted March 8, 2012 Thanks for the offer, the missing component is a roundtuit. When I get a roundtuit, it's should all come together The plan is to use an IEC framsize motor, get a plate or two laser cut so that it can mount in the same way as the original motor, and run it off a 240V inverter. Hopefully the motor I'll be able to get my hands on will be big enough to give me plenty of torque over a wide speed range, as I won't be able to run it closed loop, or at least not right away. I'm hoping 2.2kW will be ok. Once I've confirmed I've found a motor, I'll probably order a stepped pulley from RDG tools to suit the motor shaft diameter, then it'll be full steam ahead. Quote Link to comment Share on other sites More sharing options...
ejparrott Posted March 9, 2012 Share Posted March 9, 2012 I'm replacing mine with tooth belt drive, I'm still using a 2.2Kw motor, havent got an invertor yet. http://forums.lr4x4.com/index.php?showtopic=74233 Quote Link to comment Share on other sites More sharing options...
simonr Posted March 9, 2012 Share Posted March 9, 2012 2kw or so should be fine. Mine is 9kw but the only times I've seen the current meter get anywhere close to that are an emergancy stop (where it puts everything it's got into slowing the spindle down) and rigid tapping where it needs near instantaneous acceleration of the spindle. Even quite big cuts (25mm cutter) are only drawing a kw or two. A current meter is a tremendously useful tool as well as it can give you some 'feel' of how hard a CNC is working. You can see if your feed / speed is too high even when it's not making a 'bad noise' (yet!). Mine was just made out of a canibalised clamp meter around one of the mains input wires. Si Quote Link to comment Share on other sites More sharing options...
LandyManLuke Posted March 9, 2012 Author Share Posted March 9, 2012 Yup current draw will be useful to know, I can read that straight off the inverter's display. Quote Link to comment Share on other sites More sharing options...
LandyManLuke Posted March 25, 2012 Author Share Posted March 25, 2012 Quick update, The drawbar length issue has been solved for now with a spacer. I don't have a lathe (yet) so a length of tube, with a drilled out washer tacked on to each end will suffice. Before and after Now I'm waiting for the stuff to come back from the laser cutter's for the motor mount, and I need to find a new stepped pulley for the shaft. Quote Link to comment Share on other sites More sharing options...
mickeyw Posted March 26, 2012 Share Posted March 26, 2012 That looks good Luke. I see the drawbar has had some recent repair to the hex. Also, is that new motor also a dual speed device, or are you planning to use your inverter's VF ability (assuming it's that type) to give greater spindle speed choice? Quote Link to comment Share on other sites More sharing options...
LandyManLuke Posted March 26, 2012 Author Share Posted March 26, 2012 The new motor is 2.2kW @ 3000 rpm rated, so I'm hoping that using the inverter to give variable speed control will mean that I can leave the belt on the middle set of pulleys. If I have to move the belt either way for stuff that's bigger or faster its not a massive deal. Quote Link to comment Share on other sites More sharing options...
simonr Posted March 26, 2012 Share Posted March 26, 2012 I would say 2.2kw (just shy of 3Hp) will be plenty for the vast majority of things - particularly coupled to a VFD. I'll bet you will find a happy medium drive ratio with the pulleys - then never change it again! Si Quote Link to comment Share on other sites More sharing options...
ejparrott Posted March 26, 2012 Share Posted March 26, 2012 Probably true, and probably where i'll end up when i've sorted out my belt design! Quote Link to comment Share on other sites More sharing options...
Phil Hancock Posted March 26, 2012 Share Posted March 26, 2012 My friends Beaver mill(Bridgport clone) has a drawbar that has a long plain section below the hex on the drawbar, so the hex is still accessable when the spindle is fully down. Quote Link to comment Share on other sites More sharing options...
mickeyw Posted March 27, 2012 Share Posted March 27, 2012 I would say 2.2kw (just shy of 3Hp) will be plenty for the vast majority of things - particularly coupled to a VFD. I'll bet you will find a happy medium drive ratio with the pulleys - then never change it again! Si Si, I know we've kinda talked on this subject before, but if Luke's using a VFD to run the spindle motor at varied speeds, how can the table feed motor and coolant pumps also be run? (This is assuming both are left as original 3ph). Quote Link to comment Share on other sites More sharing options...
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