Homemade Lathe Headstock EXTERNAL Gearbox

[seb fontana]

Nice job on gear box..Lot of thought and computing gear ratios..I have a project in mind and need gears ..The ones you used would be close to what I need [I hope!]..Could you post or send me a link to source? Thanks, Seb..

[LMMasterMariner]

Nice job on gear box..Lot of thought and computing gear ratios..I have a project in mind and need gears ..The ones you used would be close to what I need [I hope!]..Could you post or send me a link to source? Thanks, Seb..

Recently bought 33 and 55 teeth gears from taobao at China.

https://item.taobao.com/item.htm?spm...cket=15#detail

https://item.taobao.com/item.htm?spm...cket=15#detail

Prices are for Chinese market. The same can be found at aliexpress but prices are much higher.

Best regards
LMMasterMariner

[LMMasterMariner]

above links doesn't work. go to previous page of this thread where from I copied above reply. It works from there.

[Toolmaker51]

Can't believe how many times your [LMMasterMariner] gearbox post and I cross paths. Maybe some unknown force is directing me to create one, but I don't know where to install it! To me the single critical issue is laying and producing out two opposing walls of ideal parallelism. With a large horizontal, line-boring is obvious. I'll bet few readers have such access. Pillow blocks are a logical work around, sandwiched together in a vertical mill is a good secondary approach. Regarding a layout of 6203 bearings, I'm trying to visualize getting so many bearing bores registered right and left to construct a box, not to mention some increase of thickness.
Shafts floating in a radial bearing at one end, and a tapered set on the other would tempt me, having a legitimate 4' work envelope. Auto spindle bearings have all the load and RPM range needed and plenty economical. Well directed lube becomes more important too.

I'll say again; as one doing bores, long keyways and large X-Y layouts frequently. This multi-speed gear set is still my favorite endeavor in HMT.net, deserving 'Tool Of The Week' forever, just so much to appreciate.

[LMMasterMariner]

Hello Toolmaker51,

Thanks for nice words again.
I believe that boring of bearing holes will be not so difficult task. First must fabricate 4 side plates and bottom plate. Front side and back side must be the same. Pulley side and chuck side must be the same. My plan to do it is to clamp both plates (chuck side and pulleys side) together and make them square on milling machine. The same with front and back side. Then after that must assemble the box and once I am happy with the box, need to dismantle everything and proceed with boring of the holes. My plan to do it is to clamp both plates (chuck side and pulley side) together and drill / bore first bearing hole in both plates on milling machine. Then have to install bearing with short shaft (approx. 20 mm long) in top plate. 60 teeth gear to mount at that shaft. Then need to place 30 teeth gear next to 60 teeth gear and to adjust gap. Short piece of 20 mm shaft to insert in R8 collet in order to find where to drill / bore next hole. And so on until all 8 holes are done. That way all shafts should be parallel. Already have all required material in the workshop, but first need to fabricate power feed for milling machine as I am tired of cranking.

Cheers
LMMasterMariner

[Toolmaker51]

Yes 100%. Without an X-Y [or Z] coordinate envelope to traverse an entire pair of sides, working out shaft locations individually is the only dependable alternative. Also offers previous openings for additional clamping.
I'd recommend doweling two corners to guarantee respective orientation regardless interim disassembly. The greatest repeatability is had via standard tapered dowels. With a little planning, drill and tap big ends for pull studs/ screws. They'll simplify final construction of the box too.
Another sandwiching trick is to space a few through-tapped holes in idle areas before doweling, but clamped as flat possible, then dowel prior to milling square. Then setscrews shorter than the combined thickness holds them together very well, stopping incursion of chips or burrs from holes jacking them apart. Sealing them is quite easy and varied; cap screws, Teflon tape, valve grease, drill out threads and peen in round stock...Good results peening can start with a bearing ball to 'countersink' the hole perimeter.
I'll illustrate a doweling scheme for readers and edit in; but good practice spaces dowels diagonally opposed far apart as possible, maintaining at least 1.5 diameters from edges, positioned asymmetrically to avoid matching wrong corners together. Tapered dowels don't require the effort of cylindrical and 'pull' the registry into place via the conical shape. Cylindrical dowels can shear one portion of a hole, deviating from intended position.


LMMasterMariners point about building next box after a powerfeed is well taken. For a project like this, old fashioned tooling buttons are a great substitute; moving the plate instead and minimal indicating. With decent material [a good OD finish indicates best] they'll locate intended centers within .001 readily, closer yet with sensitive test indicator and careful positioning. I don't know they are still made...But they can be made, or use small drill bushings, and of course bought used. Too many sellers think Toolmaker Buttons are some exotic deal, which is not the case, overpricing them insanely. I use drill bushings; perfect ground OD, ends very square, and come in varied length for closely placed positions.
Readers; as always, direct any questions our way. It's why we're here!
Special info discount sale today, too cold & snowy for engineering. I'm writing and rocking Spotify!

[t-maker]

fantastic job