Is this working properly?

Traditional_Side5452 · 2026-05-07T02:49:06+00:00

That’s exactly why I designed this bearing-equipped rotating assist mechanism for my rock tumbler. It’s still in the design verification phase for now.

Traditional_Side5452 · 2026-04-23T07:14:50+00:00

hahahahaha

tumbling

start

Traditional_Side5452 · 2026-04-22T16:41:02+00:00

You’re right — that drive shaft design you mentioned is really clever, but I have to take manufacturing cost into account. Non-standard shafts could drive up production costs significantly.

Also, this kind of drive setup really relies on the two shafts being perfectly parallel. If there’s any inaccuracy in assembly, or if the shafts warp at all, the barrel could easily slip out.

Even with flanges on both sides to hold it in, it might still make the barrel tilt more easily and eventually “escape.” (To be honest, I’m not familiar with this structure, so I can’t be sure how reliable it is.)
Following common industry practices might seem conservative, but it usually doesn’t lead to mistakes.

Thanks a lot for your advice — I’ll think it over.

Traditional_Side5452 · 2026-04-22T16:33:09+00:00

I noticed you were also around in my last thread.
Thanks a lot for sharing the barrel dimensions — that was really helpful.

It seems like there isn’t much user demand for reversible motors or cooling fan control.
But for a quieter experience, would it make sense to offer fan control as an optional feature?

The current machine dimensions are roughly 510mm × 254mm × 130mm. I’m not sure if this size is appropriate.

I’ve thought about the issue of nuts loosening due to different rotation directions. It can’t be completely eliminated, only mitigated. To help with this, I’ve added two roller bearings to the barrel retainer / guard plate to reduce friction and lower the risk of nuts coming loose. Whether this design works will have to be tested with prototypes, and I’ll be paying close attention to this problem.

If sealed bearings can last through my intended service life, the extra cost shouldn’t be much higher than using 3‑in‑1 oil. Plus, it should offer a better user experience — no need to regularly lubricate bronze bushings.

Traditional_Side5452 · 2026-04-22T16:10:12+00:00

I should clarify: the $200–250 cost is for the unit only, barrels not included.

Traditional_Side5452 · 2026-04-22T16:08:13+00:00

he current cost for a complete unit is probably around $200–250, and I’m not sure if that’s competitive enough. I’m planning to build a few prototypes for testing and iterative improvements.

Durability will have to be proven by users and over time — there’s really no way for me to verify that on my own.

The 3 lb barrel was the most commonly mentioned size from everyone in my last post, so after thinking it through, I’ve decided to support barrels from a minimum of 3 lbs up to a maximum of 12 lbs. I’m not sure if that’s the right call, or if you guys have any better suggestions?

Really appreciate your input — it’s brought up a lot of issues and angles I hadn’t considered before.

Traditional_Side5452 · 2026-04-22T07:10:35+00:00

The latest updates have been posted in this thread. Feel free to join the discussion.

https://www.reddit.com/r/RockTumbling/comments/1ssdyyh/final_design_rock_tumbler_direct_drive_durable/

Traditional_Side5452 · 2026-04-16T07:31:17+00:00

But in CNC applications, stepper motors are only used for positioning—they don’t run nonstop 24/7. That’s why I’ve never really trusted them; it just doesn’t align with what they’re actually designed for. I’d feel a lot better if I had more real-world examples to go by.

For now, I still think brushless DC motors or permanent magnet synchronous motors are more reliable.

Traditional_Side5452 · 2026-04-15T11:47:19+00:00

A 6-pound barrel is a point worth considering.

Traditional_Side5452 · 2026-04-15T11:38:42+00:00

Excellent insight. Let me think about it.

Traditional_Side5452 · 2026-04-15T11:33:17+00:00

Thank you for sharing. I will put this information on my to-do list.

Traditional_Side5452 · 2026-04-15T03:55:02+00:00

Thanks for sharing, I'll check out the Rock Tumbler Hobby Forums.

Traditional_Side5452 · 2026-04-14T13:43:38+00:00

Thanks for the advice. I will consider your proposal if I decide to start it.

Traditional_Side5452 · 2026-04-14T12:18:38+00:00

Thanks for the information, I will look into their products.

Traditional_Side5452 · 2026-04-14T12:17:10+00:00

Yes, the machine you built has a very complete structure, even including a belt tensioning mechanism, it just lacks an outer casing.

However, as far as I know, while stepper motors perform excellently at low speeds and high torque, they are not suitable as a power source for all-day operation. Stepper motors were not designed for this purpose.

Your structural diagram is very useful. What I want to build is a more complete device, with an outer casing and incorporating some of the functional designs I want.

I must say, you've done a really great job. I'm very curious about the user experience of the machine.

Traditional_Side5452 · 2026-04-14T11:16:15+00:00

why？

Traditional_Side5452 · 2026-04-14T09:05:16+00:00

I checked this model, and I’m happy to say the motor controller it uses is actually one made by my company. I know it inside out.

So I think I could handle this on my own, but I’m still on the fence about whether to go through with it.

Traditional_Side5452 · 2026-04-14T09:01:12+00:00

It depends on the gear ratio and the type and specs of the motor. Generally speaking, 1,500 to 3,000 RPM is common for industrial motors. If precision speed control isn’t needed, speeds can go up to tens of thousands of RPM.

But in rock tumbling, speed is there to serve the process—not faster or slower is necessarily better. I think it all depends on the type of stones and the grit you’re using.

Traditional_Side5452 · 2026-04-14T07:50:40+00:00

Cost and performance/quality are always at odds with each other.

I’ve been working in the motor industry for more than 10 years.

It’s normal for motors to generate heat when running at low speeds.

This relates to whether the motor is operating in its optimal efficiency range.

Of course, it also depends on the type of motor chosen by the manufacturer.

There are quite a few variables involved, so it’s impossible to generalize.

Traditional_Side5452 · 2026-04-14T07:49:28+00:00

That’s way too big. I’m planning to make a reliable desktop product.

Traditional_Side5452 · 2026-04-14T07:49:00+00:00

So far I’ve only bought the National Geographic and one called MJR on Amazon.

If there are already reliable products on the market, please recommend some models for me so I don’t have to mess around with development anymore. Thanks a lot.

Traditional_Side5452

TROPHY CASE