Here is a pdf for a new banjo for the mini lathe. Two banjos actually. One for fine feed and one for normal threading. It is the one Gadgetbuilder designed. Thanks Gadgetbuilder.
I liked the threading banjo and thought that with more than one of them I could reduce the setup time when changing threading gears.So I built 4 of them from 6061 aluminum. I made mine a bit different in that I used a 1/4" shoulder bolt for the shaft. The pictures show how I intend to use them. Three are preset for threads that I would use a lot and the 4th is left without gears so it is my "extra" one. In time I am sure they will have my most used threads installed in them. It helps to have two sets of change gears when doing this. I have the original nylon gears and I bought a set of all metal gears. With two sets I can set up just about any combination that I would ever need. I like to mix and match metal and nylon for a quite drive.
I used the original banjo to house the "slow" feed speed gears as supplied with the lathe. It is not too difficult to change between any of the banjos since the only hard to access nut is on the slow feed speed banjo and once it is set I don't change it. So now I have 5 banjos on my mini lathe and can change them fast.
Picture 1 is the original banjo setup with the slow speed factory gears installed on the lathe.
Picture 2 is one of the new banjos in place using a gear for the spacer and simple gearing.
Picture 3 is one of the new banjos in place using an extra lead screw spacer set up for simple gearing.
Picture 4 shows all of the new banjos laid down flat. The one on the left is using compound gearing.
Picture 5 Shows all of the new banjos standing up on the gears.
In picture 6 I attempt to show the banjo, shoulder bolt,washer, spacer,bronze bushing, steel bushing, and nut.
Picture 7 shows the original banjo and the one nut that is required to install it. Easy to install/remove with a 14mm socket and ratchet when switching banjos.
Down the road I will most likely make Gadgetbuilders fine feed banjo.
I too like the combination of the metal and nylon gears for a more quite gear train. The GadgetBuilder's MiniLathe and Little Workshop website is an amazing collection of useful mods and fixes to the min lathe. I am not sure which website published an article on modifying the mini lathe motor drive gear to have fewer teeth for a slower speed reduction but I always wanted to do this. Have you done this to your lathe for more torque at lower RPM?
Indeed our Gadget Builder aka John Moran is quite an engineer. I have spent a lot of time on his mini lathe website. Great Stuff.
Thanks for mentioning the smaller drive pulley. Sounds like a mod I need to do. Many times, especially while drilling I have hit over current and shut the lathe down. This was due in part to the very low torque at the bottom end. If I do this mod I will also add an ammeter so I can monitor the motor load. My gear is aluminum since I have the variable speed model but I don't see why it could not be replaced. Is this the web site that you were referring to above?
I remember seeing a series in the magazine The Home Shop Machinist about making simple modifications to the 7" swing mini lathes and included changing the belt drive gear to fewer teeth. In the process of searching the Internet, I found another interesting build using gear reductions on the main drive motor (see Robert's Projects: Mini Lathe Modifications ). A little more complicated than the easier Home Shop Machinist change but looks interesting.
I am not sure that a few teeth more would improve the torque that much and the drive pulley is going to be smaller in diameter than original which is fairly small already.
Roberts solution is very good and compact. He really improved torque with his gearing and since his spindle already had gears I don't imagine his mod upped the noise level much if any. I have the belt drive model and would like to keep it all belt driven. I found this 2:1 reduction belt drive that can be ordered with 14mm hubs so it would be an almost direct fit. I would have to relocate the motor to the rear where I have table space. Then I could put a jack shaft where the motor was with the new drive gear and the old 20 tooth gear (mine is aluminum). Only down side is the motor is now on the table.
Here is a link to a 2:1 reduction for $20.00. Seems like a good price.
See below for the missing link.....
Last edited by jjr2001; 10-08-2016 at 06:58 AM. Reason: missing link
JR, please add your link for the 2:1 reduction. I am very interested.
By the way, what are the specs (number of teeth) of your slowest speed gear for the banjos on your mini lathe? The extra banjo setups are a great idea for speeding up the change gear process.
Last edited by Paul Jones; 10-07-2016 at 10:58 PM.
Sorry about that Paul
One more click and I would have pasted in the link..He He.....
I hate it when that happens!!!
Here is the link for the 2:1 belt drive gear reduction missing from the above post.
HTD3M 48T 24T Belt Width 15mm Timing Pulley Belt Set Kit Reduction Ratio 2 1 | eBay
They have a wide range of belt widths and pulley dimensions. I think the 2:1 is a good starting place.
There are two PDFs on this page for mini lathe speed reductions. Pretty close to what I was thinking of doing to mine. Ralph Patterson plans
The 80/20 and 80/20 factory setup is about 256 tpi I believe. That is what I have on the original banjo. That info was from VarmitAl's site: http://www.varmintal.com/alath.htm#Finish
Which is another great mini lathe site.
All of the other new banjo gearing is the same as shown in the manual and the threading chart on the head stock cover.
Only one banjo is used at a time so my feeds are exactly the same as stock. However gadgetbuilder's slow speed banjo is much slower but I am not sure of it's speed.
Last edited by jjr2001; 10-08-2016 at 06:56 AM.
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