On Sun, 2012-02-26 at 13:48 -0500, gene heskett wrote: > You all know by now that I have one of those toy 7x12 lathes, this one with > a Speedway decal on it. > > In looking for a place to put the crossfeed motor, it occurs to me the best > place is probably on an extension bar (I have a good sized sheet of 1/4" > alu) that places the motor facing away from the operator and extending back > and under the bed. A single flat plate on the face of the carriage > extending downward could serve as the motor mount, and a belt cover could > be carved to help keep the swarf out of things. > > This assumes that a couple of nominally 1" blocks were placed under the > beds feet to raise it for motor clearance since it sits about 1/2" too low > to clear as nema 23 motor under it now. > > While thinking about that, it occurred to me to ask if it would help to add > some additional mass to the bed (this whole toy only weighs about 79 lbs) > by setting those 'feet' on another steel plate, either under the splash > pan, or in it, that would span the length of the bed and possibly help > stiffen it? > > Is it worth my touring the recycling facilities to look for something in > the 10" wide by 24" long & an inch thick, in fairly mild steel that I could > saw the end off to make the 'feet' and use the rest of it as a mass and > stiffening tabletop? > > > Thanks. > > Cheers, Gene
Based on this picture: http://coyoteden.dyndns-free.com:85/gene/emc/24.html I would try to look at the flex problem this way. Virtually place a piece of stock in the chuck and grab it with your left hand. Then grab the tool in the tool post with your right hand. Now push down on the tool and pull up on the workpiece in the chuck as hard as you can. Then visualize where any flex or slop can be -- chuck, spindle bearings, headstock, the connection between the headstock and bed, the portion of bed between the headstock and carriage, carriage, tool post and tool. >From this I don't see where bolting something to the bed feet will do much. I suppose pulling the tool towards you and pushing the workpiece away could cause a twist in the bed between the headstock and carriage. Without any foot support, the twist is between the headstock and carriage. If the headstock and tailstock feet where tied together, the twist might be shared between them. Doing this non-virtually might actually reveal some non-virtual flex. I would look at fits between parts and bearing preloads. I think some mini-mill owners have been known to lap the axes joints to get a good fit. The Craftsman AA 6" lathe users have found improvements in changing the carriage retainer to brass and working on overall fit. While I'm at it, I have an opinion on the location for your Z motor too, ... surprise. I would put it on an extension of the lead screw to the right. For my Zubal lathe, my plan is to put it on the left where the change gears used to be. I would get rid of the carriage apron and mount the lead nut rigidly in its place. Manual mode would need to be through MPG's. -- Kirk Wallace http://www.wallacecompany.com/machine_shop/ http://www.wallacecompany.com/E45/index.html California, USA ------------------------------------------------------------------------------ Virtualization & Cloud Management Using Capacity Planning Cloud computing makes use of virtualization - but cloud computing also focuses on allowing computing to be delivered as a service. http://www.accelacomm.com/jaw/sfnl/114/51521223/ _______________________________________________ Emc-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/emc-users
