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| websterz:
--- Quote from: andyf on May 15, 2011, 02:04:52 PM ---Modeldozer, Despite having no personal experience of Sieg or Real Bull mini-lathes (yours being the latter, I think), I am for some reason :scratch: a moderator of the Yahoo 7x12 minilathe group.There, some say it's better to keep the original headstock gears, to act as a plastic fuse if a tool crash demonstrates that chuck jaws are hard to machine. And others say that metal gears are noisier. I'm not advocating that you stick to plastic, but these are points which you might take into consideration. Andy --- End quote --- I will be replacing the spindle gears with metal but leaving the plastic change gear in place as the weak link. It will be much easier to replace than the others in the event of a catastrophic work interruption. |
| modeldozer:
Hi to all, Thnks for the encoragements and info. The saddle gibs will be shimed again, the adjusting screws were only added to aid adjustment wile lapping. Andyf, Thanks for the tip on the dovetail gibs, will be looking into that one. On the gears I will only put a metal one on the spindle and retain the plasitc one for the layshaft. Whwt puley ratio did you use and wher did you get the puleys? My plan was to add a jackshaft reducer as others have, but changing the current ratio sounds a lot easyer. Abraham |
| andyf:
Hi Abraham, I think the tip on the dovetail gibs came from Loply, not me. You probably already know about this source of information: http://www.toolsandmods.com/mini-lathe-mods.html - look under "Lathe mods and tools". Jose Meneses has a Real Bull like yours. Also look at Marty Nissen's 7x14 Lathe Projects, which are mentioned on Jose's home page. It is a shame that Marty never recorded the end of his project. Andy |
| loply:
I think the original pulleys were something like 14:20, I replaced them with 12:32's which I bought from bearingboys.co.uk. The ones I bought were a 5mm pitch thereby necessitating a new drive belt too, as the drive belt that came with the lathe was an unusual pitch. I stuck with the original 9mm belt width. The 32 tooth pulley was the largest one that could fit on the shaft before it would interfere with the spindle. Both the pulleys are a chippy metal of some kind, machines somewhat similar to CI but isn't. The larger one needed quite a bit of machining as it had flanges and all sorts on it, but I trimmed it up and cut a slot for the wudruff key using a file. The smaller pulley I didn't bother with the key and just used the cross screw to transfer thrust, seems to work! As stated in low ratio the top speed has reduced from over 1100rpm to around 750rpm. For me, the critical speeds of about 350-450rpm were lacking in torque previously, resulting in frequent stalling. The change is very noticeable and it VERY rarely stalls now, but perhaps more importantly it maintains the same speed easier, whereas previously even though it didn't stall it would often momentarily slow down during a cut, resulting in inconsistent finish. |
| modeldozer:
Sorry for the mixup. Loply, Thanks for the info, mine tends to hunt below 300RPM and have tried to reajusting the control as per the KB manual to no avail, hence thinking of mechanical reduction. Andy, thanks for the links, my mods/repairs is mostly based on toolandmods with some of my own ideas throughn in. The lathe is sold here in Spain under the Einhell brand and is more compatible to the Real bull than the Sieg. Abraham |
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