Aussie Lapidary Forum

LAPIDARY => Tumblers and Media => Topic started by: joshfinlay on February 08, 2014, 09:09:28 AM

Title: Building a tumbler
Post by: joshfinlay on February 08, 2014, 09:09:28 AM
Hi All,

I like to get some feedback and ideas on the best way to build my own tumbler.

I currently own a small lortone tumbler, and produce some nice tumbled stones with it but as its only small, the time taken to yield such a small batch of tumbled stone proves to be frustrating for me.

We're a successful gemstone retailer, and I'd like to produce tumbled stones (quite larger, freeform type pieces, as opposed to standard sized tumbled stone on the market).

I have a soft spot for Apatite, and I currently have 20kg+ of gem grade rough Apatite on its way from Brazil as we speak. I'd like to have something ready for when it arrives.

Now my first thought is to purchase a small cement mixer, find a way to line the inside of the barrel with rubber (perhaps some of that paint on ute tray liner??) and then seal the lid. However, I did some of the numbers on power consumption, and if my calculations are correct the motor is going to use far too much power running for so long to justify doing it.

Noise is not an issue, I already have a sound proof cement enclosure in our warehouse where it can live (used to house a compressor).

I'd really like the ability to tumble 20kg at a time.

Any thoughts would be appreciated

Regards,
Josh
Title: Re: Building a tumbler
Post by: Aussie Sapphire on February 08, 2014, 09:22:54 AM
Making a standard tumbler is relatively simple - just two shafts (one driven and one idle) powered by a motor with pulley correct size to make it run at right speed.  There is a formula somewhere on working out correct speed but it just needs to be fast enough to make the stones run up the side of barrel without being so fast that they get flung about and damaged inside.

I am not sure a cement mixer would be all that convenient for cleaning up between stages apart from the power issue.

What about using barrels like these sort:

(http://i.ebayimg.com/00/s/NjgzWDYxNA==/z/iMgAAOxyVaBSxu-q/$_3.JPG)

You can often get second hand plastic drums quite cheaply and these might be a bit easier to wash up between stages.  Or get a few and keep separate between stages.  When they wear out, get some new ones. Might need to add some rubber on the outside to improve traction on the rollers.  Another possible problem could be the round shape of interior - quite often the larger barrels have angled sides to improve run-up the side of the stones during tumbling.

We have 40 pound steel barrels available (and commercial tumblers bases to suit) but these are quite heavy and expensive plus may not be quite as large as you need.

cheers
Leah
Title: Re: Building a tumbler
Post by: darttrev68 on February 08, 2014, 09:34:28 AM
My advice would be to build a machine similar to the tumblers on the market, however make it longer (or in sections) so that you can put several barrels on at once. The issue you will have with trying to tumble 20 kg at once is the weight of the stones and water will be too much for a machine to hold. Spread the weight over 2x10kg or 4x5kg barrels and you'll have better success. You can also vary the polishing grade between each barrel.

The other positive about this is that you will not need as powerful a motor as you have on the cement mixer - less electricity consumption - though a 1/4 HP motor would be better.

Trev
Title: Re: Building a tumbler
Post by: darttrev68 on February 08, 2014, 09:46:12 AM
One day...

I remember going into an old mill and seeing all the machinery driven by large belts connected to a long drive shaft powered by a steam engine. My idea is to build a similar system that drives all of my cutting and polishing machines, set up over a long steel bench, however the engine would be a clock-work motor with a large and powerful spring. This spring would be wound by a counterweight attached to a windmill. When the wind blows, the spring gets wound up and I can cut and polish electricity free.

One day...
Title: Re: Building a tumbler
Post by: joshfinlay on February 08, 2014, 09:50:04 AM
Hi Leah, Trev,

Thanks for your quick response.

I do think a bit more thought needs to go into building this, and originally I was hoping to get away without having to build too much of it (ie. the cement mixer idea) but in order to get the power consumption I need to make it viable, and the ease of access to load and unload it, I need to stick with the similar concept as commercially available tumblers.

I think fundamentally the factor needs to be cost of production, so instead of looking at it thinking "i need a 20kg tumbler", I will research and purchase the motor that is going to most cost effective to run for extended periods under load and then build the rest around that.

I like a plastic drum idea, do you think the inside will be soft enough for the stones when it comes to the final polish stage, and do you think it will be durable enough for the rough stage without eating the inside out? I imagine the stones alone are going to be much harder than the plastic of the drum, let alone any of the tumbling grit.

I can probably reduce the load on the motor by using a series of belt driven pulleys to step it up or down and get a better speed-load result.

I do very much like the idea of running two barrels, then as you say Trev, I can have two batches going at once at varying stages. It also means I can have two totally different batches going at once (ie. Apatite (mohs 5) in one, quartz (mohs 7) in the other) so they don't damage each other.

I appreciate all your input, and it will definitely help my decisions on building this.

Regards,

Josh
Title: Re: Building a tumbler
Post by: Aussie Sapphire on February 08, 2014, 10:07:48 AM
The other positive about this is that you will not need as powerful a motor as you have on the cement mixer - less electricity consumption - though a 1/4 HP motor would be better.
Trev

We quite often fit 1/3 or 1/2 hp motors to various machines as they only cost a very small amount more and use only the electricity they need - ie. a larger motor running easily is often better than a just enough motor running at full capacity.  Andrew knows more about this but that is what I understand from how he chooses motors for various jobs.

Agree with the idea to run more barrels rather than one huge barrel.  Apart from spreading load more easily, the cleaning between stages will be a lot more difficult for larger barrels. By using multiple barrels, you can keep the stages separate.

Commercially available tumblers do this and the principle can be scaled up.

This C300 runs three 12 pound barrels:
(http://www.lortone.com/images/C300_12.jpg)

This C40 runs one 40 pound metal barrel or same base can run two 20 pound barrels of similar style or two 12 pound rubber barrels:
(http://www.lortone.com/images/C40.jpg)

Really dont know how the plastic drums would work - it just struck me as the type of thing that could be sourced cheaply and might work.  They are supposed to be water tight but sometimes you have trouble with seals when you have used them with abrasive grit a few times.

As mentioned, I would be a little worried the stones might not run up the round sides well enough.  The steel barrel we sell is hexagonal and the 12 pound rubber barrel has an angled interior (10 sides or so inside) to help the load tumble efficiently. 

Cheers
Leah
Title: Re: Building a tumbler
Post by: Gemhunter on February 09, 2014, 08:40:43 AM
One of the members at my Lapidary club has made his own tumbler out of an old washing machine motor, its a primitive design but does the job just as well as a lortone. He uses both the plastic barrels but says the seals do leak here and there. He also uses the hexagonal barrels with the rubber seals with much success.   
Title: Re: Building a tumbler
Post by: As I in does tries! on February 10, 2014, 05:43:50 PM
Greetings Josh, firstly welcome to the forum, 20kg of rock is not a lot, in fact it just fills two
Lortone 12lb rubber barrels.

A Lortone QT12 (1x 12lb) / QT66 (2x 6lb) would be ideal for stage 1 with Fixed 80 (60/90) grit, for
the other stages a virbratory a single barrel Belt Lott-o or Gyroc model B with upgrade packs, it
will speed up the time it takes to finish your rocks, normally it takes about a month on a rotary
from F220 to polish, where as the virbratory can finish it in 10 days with a saving of both
grit & polish.

If you wish to Do It Yourself you will find plenty designs here.
Rock Tumbling Hobby Forums: Home Made Equipment (http://andy321.proboards.com/board/11/home-equipment)
But please note this site is very picture heavy & not suitable for a dial-up internet connection.

Please check out my Sticky's below.
Title: Re: Building a tumbler
Post by: Bucket on February 10, 2014, 07:01:14 PM
Sorry Andrew, but isn't 20 kg the equivalent of about 44 lb not 24 lb?  I know it's been a while since we changed over but I seem to recall that 1 kg = 2.2 lb.  I stand to be corrected as I don't do any tumbling.
Title: Re: Building a tumbler
Post by: Aussie Sapphire on February 10, 2014, 07:24:21 PM
Using weight only when loading a barrel can be a bit confusing.

For eg, a QT12 is rated as 12 pound (ie. approx 5.5kg including weight of barrel and all contents) and I would not want to be pushing much over that limit on that particular tumbler.

But the Commercial Series tumblers or a home built tumbler using a larger motor could easily handle extra weight in that size of barrel.

Yes - 20kg is about 44 pounds - tumblers weight ratings usually include weight of barrel and all contents but this can be adjusted depending on type of motor used. 

I have always thought describing tumblers and barrels/bowls in terms of volumetric capacity makes more sense but no one seems to do that.

cheers
Leah
Title: Re: Building a tumbler
Post by: As I in does tries! on February 12, 2014, 03:11:40 AM
Greetings Ladies & gents, firstly rotary & or vibratory tumblers are filled by volume not weight
& yes 20kg = 44lb.

The heavest 12lb barrel was 18.6kg (41lb) 75% full of Gold Tiger's eye on a Lortone QT12/66.

Only Homberg & Brusius (http://www.homberg-und-brusius.de/english-text.html)  Rotobarrel (http://www.ukge.com/en-au/Lapidary/Stone-Tumblers/Polishers__c-p-0-0-14-252.aspx) near the bottom of the page specify their tumblers by volume.

Homberg & Brusius's  TRM-1A, TRM-2A & TRM-5 appear to be rebrands of the Lortone 3A , 33B &
QT12 with white rubber barrels.

Rotobarrel's 3Litre & 6L barrels are comparable to Lortone's 6lb & 12lb rubber barrels & have
almost the same dimensions as Lortone barrels, however Rotobarrel have a side opening
window & they are at the top end of the market in price.
Title: Re: Building a tumbler
Post by: Bucket on February 12, 2014, 09:27:01 AM
Thanks for clearing that I up, good to know I'm not loosing it completely!
Title: Re: Building a tumbler
Post by: As I in does tries! on February 12, 2014, 11:34:25 AM
Tumblers weight ratings usually include weight of barrel and all contents but this can be adjusted
depending on type of motor used.

Greetings Ladies & gents, [Leah] that statement is only true when you have got a kiddie tumbler
that is guarenteed to break within the 1st month.

All Beach & Evans tumblers come with a five year guarentee.

Beach tumblers are constructed by Beach Lapidary Limited.
Evans tumblers are constructed under licence by Kimber-Allen UK Limited, their main product line
is church organ component parts.
Title: Re: Building a tumbler
Post by: Aussie Sapphire on February 12, 2014, 12:14:08 PM
With respect, it is not much use to recommend a company that is not practical for Australian users to use.  This is the Aussie Lapidary Forum - no problems for our Aussie members to buy from overseas but not feasible when very similar products cost very much more.

For example, the CR2 tumbler from Beach & Evans costs £167.50 with two rubber barrels equating to about $310 AUD before you factor in expensive shipping from the UK.

The equivalent size Lortone costs $185 in Australia - a fairly sizeable price difference even before you add in shipping.

I like the cogged belt of the CR2 - that certainly would help with belt slippage but not so sure about the lid sealing system - I like the double lid system of the Lortone better.

I  definitely do not agree that the Lortone tumblers are a toy type tumbler.  In line with the manufacturers recommendations, we advise not to significantly exceed the rated weight capacity of the tumblers.  But when used correctly, they will last for many years of work.

We and most other Australian suppliers offer 12 months warranty on Lortone tumblers (most equipment actually) and I cannot remember the last time we had to fix a warranty issue that was not transit damage so they certainly will not break within the first month.

The point I was trying to make which you seem to have misunderstood was that tumbler barrels should be filled with respect to volume BUT also having consideration to the advised weight limit of the tumbler.  In some cases (such as the commercial tumblers), a barrel that is advertised at a certain weight may be safely loaded up more heavily because the motor that is fitted can handle more load.  So take notice of weight ratings but with reference to the size and type of motor that is fitted - it is not always a firm rule but rather a guideline.

Getting back to the original topic, when building your own tumbler, it is easy to fit a motor that can handle the job easily and then you can pretty well forget about the possibility of weight overload.

cheers
Leah
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