Home » 2014 » April

Archive for April, 2014

Cleaning bolts in a tumbler – PART 2

Posted April 2, 2014 By Admin

Part 2 of this article covers use of a rotary tumbler for this job.
Barrel_1Barrel_A_Before2In this test, we have used both #80 and #46 silicon carbide grit as well as medium cut ceramic media (triangle shape) – a bit water is added for the rotary type tumblers – aim to fill the barrel up to about 2/3 full.

This photo shows the batch before it was tumbled – note some of the pieces were extremely rusty and others just greasy and dirty. Again, we would expect better results if parts were degreased before tumbling.

The 12 pound barrel can fit larger pieces in compared to the Gyroc tumbler (note the large cog which was too large for the Gyroc A) has cleaned up well in the larger 12 pound barrel.  As a size reference, the base of the purple sieve is about 10″ (250mm).

Compared to the Vibratory tumbler, the bolt threads did not clean up quite as well and it took a little longer to get this finish (about 2.5 hours). The Lortone tumbler runs quieter. We used the QT12 for this test but you can get a triple barrel tumbler (same 12 pound rubber barrels) for larger scale tumbling. 

Barrel_B_After2

Cleaning bolts in a tumbler – PART 1

Posted April 2, 2014 By Admin

Every now and then we get asked about cleaning bolts in a tumbler so we thought it was time to post a few pictures with extra information.  Tumblers are great for cleaning up all sorts of metal objects as it takes a lot of the tedious hand-work out of the job. There are a few different ways to do it – Part 1 of this article deals with tumbling in a Vibratory tumbler:

Vibe_1Vibe_2

This test batch included a selection of old bolts and other items – some extremely rusty, others just very greasy and dirty.

The test machine is a Gyroc A tumbler (the medium size).  In this test, the tumbler was loaded with about 4kg of medium cut ceramic media (medium abrasiveness, triangle shape) – about 4 heaped tablespoons of #80 grit silicon carbide and a small amount of water was added along with the test parts.

The parts were tumbled for about 1.5 hours – just before removing and rinsing, additional water was added for about 10 minutes to make the clean-up easier.  Note that normally we would recommend degreasing parts before tumbling for better results – we did not bother with this small test batch.

Vibe_3

 

Vibe_4

After almost 2 hours of tumbling, the parts came out very clean (even better if degreased before tumbling).  However, there are a few things to consider with the Vibe Tumbling Method:

1) Using coarse abrasive grit in a vibratory tumbler will wear the barrel faster than in normal usage.  The tumbling is faster and more effective but you need to factor in more frequent replacements of bowls.

2) The donut shape of the tumbler bowl does restrict the size of piece that can be tumbled – they need to be small enough to move freely around the bowl.

3) Vibratory tumblers are more noisy than the rotary tumblers.

Vibe_A_Before

Vibe_B_AfterThese photos show a before and after shot of the pieces (note the large cog was too large to fit and was subsequently tumbled in the rotary batch instead).

There is a little rust remaining on the thread of the largest bolt – this would have been improved by degreasing prior to tumbling.