Ideas on a rod mill

[Plbnyn]

Now that I have hand crush ore and will soon have a jaw crusher operation I read about a rod mill and looked into the design
The question I have would a wood lathe work well for a rod mill. Multiple speeds face plate mounted tail stick with a bearing and a pair of rollers mid span for additionL supportSo the
Owe with experience with a Rod mill will this work and even those with a good mind can you see this working

Any feed back would be greatly appreciated

 

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[arizau]

In theory it should work. In practice you will probably have to deal with at least two issues. The load will be unbalanced at all times so it will want to walk your lathe all over your shop. Also since it is unbalanced it will probably play heck with the bearings. Go to this thread for a better idea for a rod mill. Just set aside that the design is for concentrates. It is in fact a rod mill and will handle any rock feed as long as it is reasonably sized. http://www.treasurenet.com/forums/panning-gold/456622-simple-solution-fine-gold-recovery.html. Do not expect the same results though as the grind time will be longer and result in degradation of the gold in size.

 

[bobw53]

The load will be unbalanced at all times so it will want to walk your lathe all over your shop. Also since it is unbalanced it will probably play heck with the bearings.

Shouldn't matter all too much, playing the rod mill game, probably no more than 150rpms, tops. About the speed you dial a rotary phone (the yung'ns can google that, or go see one at the Smithsonian.)
I've had an 8600 lb machine start walking away with a 2 lb slug in it an inch off center.. But that was really getting after it. It is definitely a real concern, but at low revs I'm 99.9% sure he'll be OK. With
a wood lathe, I would(wood?) be concerned about being able to get the revs low enough so that it doesn't go walking across the shop.

I've done a bunch of tumbling on several lathes, in nothing more than a coffee can. Toss your media in, ceramics, plastic abrasive pyramids, rouge impregnated walnut shells or whatever, tape the lid down and let it go
at a low RPM. I don't see why it wouldn't work with rods also.

 

[KevinInColorado]

The desired rpm is only about 70 or so. Fast enough for the rods to ride up the side and then fall. Too slow and they don't ride up high enough to fall. Too fast and the rods do a loop-the -loop and don't fall at all. Also, in Clarkson's testing, he found the ideal run time was surprisingly short - like 10 minutes!

Edit: as mentioned below, I built a little bench-top rod mill to learn more. I only put a few tablespoons of material in at a time. It works well though and this winter I plan to run some more experiments to see how much wet vs. dry processing matters. Also, even after running for over 30 minutes, not all the +30 mesh material was crushed but I did obtain some nice flattened gold pieces. My hypothesis is that you don't need to crush all the material to get all the gold since pieces of homogeneous material (i.e. Solid grains of iron sand) would not crush as easily as grains with discontinuities in them (such as some gold!)...you just need to run long enough to crush the grains with gold in them, then you can toss out the rest with confidence. This is just my theory right now. I'd love to hear what others learn...

 

[Plbnyn]

I like the ideas and interest. I have had a lathe hopping around the shop before and with sand bags or enclosed box around the leg/base I was able to turn bowls at max diameter regardless of mass and slight or great out of roundness. The lowest I have seen a lathe turn is 12RPMS and that was a lathe with a 69 station wagon 3 speed transmission.
I like clarksons Idea, problem being I have ore and no money (kind of a familiar thread here), so building that device is out right now, a suitable lathe on craigslist was 200.00
I try it and admit to my failings when they happen. Keep the thoughts coming........................

 

[bobw53]

Keep the thoughts coming........................

A few things I've done with a lathe.. That you really shouldn't do. Maybe give you some ideas.. Also, I think Kevin up there, his rod mill is made out of an old printer.

Using a little Atlas to spin a rotary table. The "drive shaft" is a telescoping piece off an old pop up canopy.

Another horrible thing... I needed to slow this crappy little bandsaw down, cutting nylon sheet and it was melting it, not cutting it.

Another rotary device that I just pulled out yesterday. When I built my furnace, I needed to mix up 6-8 pounds of refractory cement per batch.
I borrowed a run of the mill Horrible Freight cement mixer, but it was too big... So I built (hacked together) this little guy. Its a 90 degree worm
gear box, and a crappy little motor that somebody was throwing away. It runs 45 rpms. I was using that old pot, and then I went to a bucket.
It just slides onto the shaft.

I pulled it out yesterday to bang up some caliche/cemented gravels.

Gravel... Before, All plus 1/8"

After, 2 pans of plus 1/8" and a pan of -1/8". I sure hope there is some gold in there.

On my first attempt, it wasn't completely dry, I succeeded in making a bucket full of cement balls.



I'm thinking lathe(because everybody needs a lathe) to driveshaft, to rollers. Then you aren't limited on drum size, don't have to worry about
blowing up spindle bearings or having the machine walk away on you, and the driven roller(s) will give you
a gear reduction, which should give you more control of the RPM's, and let you hit the sweet spot, where
as Kevin said, lets the rods ride up high and fall. You could also use a swamp cooler motor and a few belts, but then
you don't as much control of RPMs and you don't get to buy a lathe.

 

[Plbnyn]

i never thought about using the rollers as the applied rotational force.... I was thinking of using wheels (follower bearing/support) like i used on a machine lathe to support long stock between the head stock and the tail stock. I will have to swoop in an buy the next gerar reduction motor I see that is a cool use for low speed, the atlas turn table is ingeneious great use of a tool that really is very specialized. I think that the lathe is a good platform to start with....

Keep the alternative uses of tools coming I like it.....

 

[AuTSaurus]

Plbnyn,

Hello. Thought I would chime in here with a suggestion. In September, 2010, on a different forum, a person posted
a homemade rod mill that he had designed and constructed from an old motorized reel type lawnmower.
To date, it has been the best homemade design I have found in my online searches.

It impressed me so much that within one day, I searched craigslist in my area and found the same type of
mower for sale at a GREAT price and purchased it, to make the same type of mill. I have yet to finish the project, but
that is entirely my problem and situation, not anything to do with his design.

That person is also a member of this forum, as I did a member search for him before typing this post, in order to possibly help you. That member is Kid Saxon, and if you send him a PM, he can probably give you some advice and possibly share some pictures. If he is unable to, PM me and I will try and find his earlier posts, and possibly pictures from the other forum.

Hope this helps.

Greg

 

[Plbnyn]

Greg,

Ill look that up next week when I am back at a computer. Appreciate the info found out the other day that two heads are better than one... And the ideas that I am getting here on this forum have helped out greatly
Plbnyn

 

[kcm]

Randy Clarkson has done some interesting work concerning rod mills. There are 3 .pdf files that explain his design, how it works, speed of operation, etc.

The 4-page link is:
https://yukoncollege.yk.ca/downloads/Grinding_for_Gold.pdf

Another 39 page .pdf is at:
http://www.geology.gov.yk.ca/pdf/141114_Nov1014_Grinding_for_Gold_Presentation.pdf

The link to the final .pdf (56 pages) article is: http://kpma.ca/assets/files/grinding-for-gold-report.pdf

In these articles, among other things, is specific information concerning building one of these rod mills for your own use. Has been a while since I read them, but I know that the 4-page article had info that the 56-page final didn't have....that is, unless I just didn't read close enough!

 

[Mad Machinist]

Yea, your idea would work for awhile. At least until the bearings in the headstock and tailstock give up from the beating they are going to take. When the rods fall, they will cause "impact forces" on the bearings. Now depending on what type of bearings you have will determine how long the lathe would last being used for this. If you have a higher end wood lathe, then I would discourage you from trying this. If it is a cheapo Chinese copy, then I would probably try it and work towards a better set up.

I am not trying to discourage you, just give you a heads up on what is going to happen. If the bearings do go out in a short order, I can probably find a cheap set of replacement bearing if they are the roller or ball bearing type. Just need the numbers of the bearing races.