Best radial ball bearings according to redditors

Honestly I should just buy a 20 pack of these and then print a frame that holds them all in a circle so the hose can have a perfectly smooth track to go through

Use ceramic bearing balls. ( https://www.amazon.com/uxcell-Making-Plastic-Bearing-100pcs/dp/B07TJCNP5G/ref=rtpb_1/137-8536023-0703351?_encoding=UTF8&pd_rd_i=B07TJCNP5G&pd_rd_r=563eb58a-4463-4975-9697-c52025b89697&pd_rd_w=JOdjh&pd_rd_wg=VS4cH&pf_rd_p=93b3b076-f930-43df-b8f9-7a7b49a1950c&pf_rd_r=JKVQ2BZ5SJNK78NAA3KS&psc=1&refRID=JKVQ2BZ5SJNK78NAA3KS )
Or steel ones ( https://www.amazon.com/uxcell-Carbon-Bearing-Precision-100pcs/dp/B07SV6QSR3/ref=mp_s_a_1_4?keywords=6mm+bearing+ball&qid=1572155597&sr=8-4 ) warning: if these hit something hard, they WILL throw shrapnel (think flying knives).

I don't understand how he managed to spend 40 euros on that though. 40 Euros is ~45 dollars.

6003 for $10:
https://www.amazon.com/SKF-6003-2RS1SKF-Single-Ball-Bearing/dp/B0767N6GPF

6204 for $10:
https://www.amazon.com/6204-2RS-Sealed-Bearing-20x47x14-Bearings/dp/B00IK4KX4G

OP overpaid by more than double for bearings.

Formula track hubs take a 6000 cartridge bearing. The "6000" is just a name for 10x26x8mm (Inner diameter x Outer Diameter x Width) bearings.

I've just replaced mine on my winter bike with VXB bearings and they've been great for wet conditions. I've used some other bearings as well on other bikes, but the VXB's seem to be my favorite value so far. Actually, I've got VXB's on 3 wheelsets as of now.

If you only ride in dry conditions, you could go for a "better" bearing, which should give you less drag. But usually, "better" (ceramic) bearings often have non-contact seals, which definitely don't seal water and dust out as well as their labyrinth-sealed or contact-sealed counterparts.

Just look up 6000 series cartridge bearing, or just find a 10x26x8mm bearing by Phil, Enduro, or some other reputable company. If the name of the bearing has some letters and numbers after it, like 6000-2RS, it usually describes the seals used. So a 2RS is 2 Rubber Seals.

EDIT: Stuff

It'll rotate but not smoothly. I'd recommend you use turntable hardware instead. Read all the comments on the page to get a better understanding.

Also, remember that if your room is 4x4, a 4x4 square won't rotate in it, you'd have to make it circular or a smaller square.

2 [Neodymium Cup Magnets] (https://www.amazon.com/dp/B01NAEF59W/ref=cm_sw_r_cp_apa_wrZ6ybYNF05FF) glued together (Note the magnets will repell slightly because they're backwards, I held them together while they dried with a potato bag clip)


And a [3/4" Diameter Steel Ball Bearing] (https://www.amazon.com/dp/B008L3V098/ref=cm_sw_r_cp_apa_isZ6ybP374PVF)

The glue I used was Gorilla glue, the one that dries white and expands some. It worked really really well. I could scrape it off with my knife if there was too much but it's also incredibly strong. I recommend this over soldering because the ball needs a tiny bit of space as a track to roll around and because the glue expanded it provided a track to go around. Otherwise solder it if you have a mini washer to use as a spacer.

I've also dropped it on hard floor a few times and no marks or any signs of damage.

The only real difference from this an the Orbiter is that the centers are incredibly attractive unlike the Orbiter, they are also not as concave but the ball will still fit into the divot. But because of the high attraction it won't roll around in that divot but you can still run your thumb around the stationary ball which feels nice. There is also a hole in the center of this so I can expand on this toy too :)

EDIT:
This is the weird big bearings on the back of the V1's.

• Cheap
  
• Pretty
  
• Expensive
  
• Ceramic?
  
  What to search for:
  6804 20x32x7mm
  
  There's shit everywhere.

I used this.

One Square 3" Inch Lazy Susan Turntable Bearing - 5/16" Thick & 200 LB Capacity https://www.amazon.com/dp/B00ZSQSWTM/ref=cm_sw_r_cp_apa_i_dziuDbB1ZASZ4

Already a lot of great answers by clever people here! I can add a bit on motors and electricals, but I also want to say that you're probably underestimating how big a 3' arm is. Imagine that on your desk- it takes up half a table! Sizing the motors for static torque alone doesn't work well, as the inertia at the end effector increases with length^2 which is proportional to dynamic torque, speed, and vibration. Larger limb sections are also heavier and more complicated to make, which makes them even more heavy. Sizing down a little bit will make the arm dramatically more stable and performant.

> Belts or Gears for the actuators?

For 3 lb @ 35" you're looking at a minimum torque of 12.2 N-m at the shoulder. That will require reduction. Belts are far cheaper than gears, especially if you have a 3d printer- plastic pullys work great, although they need to be well glued to metal shafts (NB that a shaft key will greatly reduce strength and durability). Red loctite is great for that. A single belt reduction can do 5x, although you can do 10x+ with idlers. Mcmaster is a good place for belts, but amazon has a small selection that can be cheaper.

Note that belts can be very rigid: highly tensioned, fiber reinforced belts at moderate torque (otherwise the teeth start pulling out) are actually stiffer than most gears, which have a grease film and a gap between teeth that has a slight initial give/backlash. The reason you switch from belts to gears is because you need to tension the belts more tightly for higher torque. Once the tension becomes hard on the bearings and gearbox frame, you switch to gears. Basically you want to avoid gears if at all possible; they're expensive, hard to find, and hard to mount without metal backplates and the ability to cut bearing mounts. SDP/SI is a good place to get gears.

> Once I know how much torque I need, how do I know which type of motor is best for me? Stepper, Servo, Brushless?

Depends how much you want to spend. Hobby servos won't work for a 35" arm, even the $350 dynamixels. You also don't want to be designing your own brushless drivers, and the range of robotics controllers for bldc is limited. You are basically stuck between NEMA 23 and odrive.

NEMA 23 is the cheap choice- you can get very big NEMA 23s on amazon, hook them up to a single-stage 5x reduction, and have gobs of torque and good control. You can even get NEMA 34 for affordable prices. The drivers are stupidly cheap- for <$70 all-in you can have an arduino-controlled joint with 15 N-m of torque and top out solidly over 500 rpm. Add a couple heat sinks and you can increase that a lot- 500+ watts no problem, or 7 watts per dollar.

Downsides are you don't get any regen (not so important on an arm), low/no backdriveability (although this can be nice since the robot usually holds position when it turns off), very loud operation, low efficiency, and pretty low acceleration. Brushless motors require higher reduction and closed loop control, but are quiet, efficient, and can be used to build very responsive + high regen robots. Driving them is the weak link: the 56 V odrive dual driver cost a whopping $150. However for $70-80 per motor you get 40-90 amps continuous for 2 to 5 kilowatts, WITH regen and accuracy to >512 steps. That can be over 20 watts per dollar for the motor, reduction, sensors and driver. The limiting factor is even finding motors that can handle that power.

If your budget is <$500, go for steppers. If it's >$800, I'd go for brushless. You'll get an immense amount of speed and power, both of which are very good for an arm with a 3' reach. Note that 3' is a very large arm- the weight of the arm itself will be very limiting if you don't used fairly sophisticated techniques. 8"-12" sections are a hassle to 3d print. Rotational inertia increases with reach^2 so you'll need quadratically more power for the same acceleration (and to fight wobble). A 26" arm will require only half the power.

> Do I start my design from the end effector or do I start at the base?

I'd start at the end effector- that will set your payload weight and the torque required at the next joint, and so on back to the shoulder. Doing it the other way requires a lot more iteration.

The one thing I always say on posts like this is to learn how to use bearings. Bearings are the #1 cause of wobble in poorly designed arms, and the easiest way to tell if the designer had any clue what they were doing. Use 608 bearings for everything you can. They're incredibly cheap and precise because they're used in skateboards- 20 to 50 cents each. They're deep groove bearings, which are excellent for machinery, and can take 300 lbs radial and 150 lbs axial static load and 2-3x that for dynamic load. They're easily a 50x better value than any other types of bearings. If you want other bearings (maybe very large thin section) go to onlinebearingstore, despite having a 2000s era website/name they're really great. Unrelated, theoringstore is also really great.

The most important thing to know about bearings is that they always, always need a preload. The bearing will not meet specs if it does not have some axial force. It will have a very noticeable play and will wear out quickly. This is why you always use bearings in pairs- not because they can't take it, but because you can't preload a single bearing. You need two bearings to be pressed together. I like disc springs for this, but shims and even just bolts also work well for providing the axial force. You can usually just set your preload by feel (so make it possible to bolt down one bearing closer to the other), but if you want to do the math it's good to aim for an axial force of 50% of the maximum radial force you expect. That can come from static load, or torque from twisting the bearing.

I just went to Amazon.

I got these various bits and bobs:

608 Bearings (about 50 cents a peice)
M2 screws + nuts
M3 Screws + nuts
Got those in, saw that they were philips
Ordered some M2+3 screws + nuts that were hex
Washers came with most of those sets
Some springs, compression and otherwise
Steel ball bearings (I actually don't know what I'm going to do with this)
Nylon Lock Nut set

Might run ya 30-40 bucks but you got a few ways to put things together.

Edit: Some links to get you started

M2 Screws
https://www.amazon.com/gp/product/B01J7NM9JA/ref=oh_aui_detailpage_o03_s00?ie=UTF8&psc=1 - $15

M3 Screws
https://www.amazon.com/gp/product/B01J7IUBG8/ref=oh_aui_detailpage_o03_s00?ie=UTF8&psc=1 - $15

608 Bearings
https://www.amazon.com/gp/product/B002BBICBK/ref=oh_aui_detailpage_o03_s01?ie=UTF8&psc=1 - $6

Nylon nuts
https://www.amazon.com/gp/product/B000K7M37G/ref=oh_aui_detailpage_o03_s01?ie=UTF8&psc=1 - $10

Springs
https://www.amazon.com/gp/product/B000K7M36W/ref=oh_aui_detailpage_o03_s01?ie=UTF8&psc=1 - - $8

I used

1.26" Neodymium Cup Magnets (qty 2) from Amazon
3/4" Diameter Steel Ball Bearing (qty 1) from Amazon but only had a 6 pack

Yeah, regular 608s. https://www.amazon.com/gp/product/B07C6FL8TW/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

I'll just this here, you'll be finding it helpful: http://www.amazon.com/gp/product/B002BBICBK/

Found it.
6000-2RS Bearing 10x26x8 Sealed Ball Bearings

https://www.amazon.com/gp/product/B002BBFDGM/ref=oh_aui_search_detailpage?ie=UTF8&psc=1

Or $9.95 with free shipping on Amazon.

From amazon

Sorry, it's 3/4 inch...

http://www.amazon.com/gp/product/B008L3V098/ref=oh_details_o01_s00_i00?ie=UTF8&psc=1

Here's a pic of it. The Tower
It stands a little over 6ft tall. It's 5 tabletops, and 4 sets of legs, with the 5th top acting as the base. Each table is 21.5 inches square and the tops of 2in tall and the legs 15.5. It sits on top of this, so it can rotate. The joining plates come from Home Depot. Here's a pic.
I originally joined them with flimsy screws and plastic joiners that came from Ikea's free spare parts areas, but I didn't trust them once the tower would be fully loaded. I'm not much of a craftsman, but I'm happy with it. All told it cost me about $45. ($5 per table, + Joining plates/screws + Lazy Susan)
I mostly use it to hold games that get played a lot, so it's not a shot of my whole collection.

Under 15? The best thing you can buy hands down is this:
https://amzn.com/B002BBQDW0

That was an easy question ;)

It’s tough at the beginning getting all things. I was like you, I went for hardware shops for brass nut and bearings but I ended up with nothing, my only choice was to order online. I live in Malaysia as of now and my online sources are the Chinese Taobao, or the Malaysian Shopee and Lazada.

For bearing, you can check the full list at:
https://www.bearingworks.com/bearing-sizes/#table-of-contents

Most common bearings from what I know used for ring spinners are 6803/61803 and 6703, some other choices are considerable like 6903. Based on the link above you can see the differences of each. Back to your question, I can only suggest getting them online like Amazon if you live in the US, like this:

https://www.amazon.com/Ceramic-Bearing-6803-2RS-17x26x5mm-61803/dp/B0758F464W/ref=mp_s_a_1_1?keywords=6803&qid=1574536512&sr=8-1

You can look around for cheaper ones, I got mine for about 3$ from Shopee.

For a brass nut, something like this would do:

https://www.amazon.com/FidgetKute-Select-Size-M10-M12/dp/B07RB1B9VX/ref=mp_s_a_1_6?keywords=brass+nut+m24&qid=1574536643&sr=8-6

These are just examples, you should choose carefully the type/size of the nut based on your liking and the size of the bearing you picked. I also suggest Aliexpress, they have good prices.

About the lead poisoning, I really have no idea, I think it should be fine as long as we don’t digest anything from it, I have to do more research to know about it.

Anycubic All Metal Right Hand MK8 Extruder Aluminum Frame Block DIY Kit for Reprap i3 3D Printer https://www.amazon.com/dp/B0196B285I/ref=cm_sw_r_cp_api_yI-vyb8AGEEGK

You should also get these: uxcell® 5 Pcs Silver Tone 10mm x 4mm x 4mm Sealed Premium Flanged Ball Bearing https://www.amazon.com/dp/B00G9W20VU/ref=cm_sw_r_cp_api_lJ-vybPV8A1NM

You need the bearings instead of the one in the above kit if you keep the original drive gear on the machine. The new kit has a new feed gear, but it will change how much is fed, requiring you to recalibrate your printer.

For less messy amazon links you can extract the part after "/dp/" in

https://www.amazon.com/Ceramic-Bearing-8x22x7-Bearings-VXB/dp/B002BBQDW0/ref=sr_1_3?ie=UTF8&qid=1484208187&sr=8-3&keywords=vxb+ceramic

and make it:

https://amzn.com/B002BBQDW0

BEEP BOP

Plz send any recommendations via PM

OnDaq,

This one from Amazon seems like a pretty good deal.

https://www.amazon.com/VXB-Ceramic-Miniature-Bearing-8x22x7/dp/B01JKBUR1Q

It's a full ZrO2 bearing. There are two types of ceramic bearings (Si3N4 Silicon Nitride, and the ZrO2 Zirconium Oxide). Then you have full or hybrid. A full means that all components of the bearing are made from those elements. The hybrids will usually have the ceramic balls and the rings/races are made from some other material. Just make sure the size matches to the existing bearing in your spinner if you're buying a replacement online.

Regards,
Nate

I'm pretty new to this too, I bought my Ender 3 Pro around the same time as you. Quiet printing is pretty high on my list as well as being able to print high-temp exotic filaments in the long term while maintaining reliability.

First upgrades I purchased were stiffer bed springs so I would be less likely to throw the bed out of level while removing prints or working around the printer and Capricorn XS tube since it has a more consistent internal diameter, fits closer to the filament, and can work with slightly higher temps. I also picked up a pack of bowden couplers recently as I noticed the end nearest the extruder is sliding past the coupler jaws on de/retraction; don't worry about that unless it's an issue for you. That's about $30 alone since I don't have a supply shop locally and have to order those parts in bulk. I had a Pi 3B laying around unused and flashed Octoprint onto it. Highly recommended. I have a replacement Noctua hotend fan, buck converters, and 5015 blower on order to quiet the fan noise; about $32. Just replaced the Meanwell psu fan with a 60x25mm Noctua I had lying around (Note: there may be better options in the 92-120mm range to replace part of the PSU housing, but that's what I had laying around). Next upgrade coming is the SKR Mini E3 with TMC 2209 drivers ($28) to eliminate almost all of the stepper noise. Also looking into a replacement for the control board fan and some vibration isolating feet for the frame. As far as higher temp printing I haven't made a lot of progress aside from buying a titanium all-metal heat brake ($11) winch I have yet to install or inspect, and looking into enclosure and electronics relocation avenues.

Either way the mods I purchased came in at around $100 US which should quiet the printer and help with reliability. Also looking into picking up a good M3-M4 bolt kit if any exist in the US.

Here are some links to the things I picked up and will, which may be helpful if you're in the US. Mostly from Amazon.

Type | Name | Link | Price
---|---|----|----
Reliability | 8mm x 20mm yellow springs | Link | $6.98
Reliability | Capricorn XS Tubing | Link | $11.49
Reliability | PC4-M6 / PC4-M10 Pneumatic Bowden Fittings | Link | $11.99
Silence | Noctua 40mm x 10mm 3-pin fan | Link | $13.95
Silence/Various | LM2596 Adjustable Buck Converters | Link | $10.95
Silence | 24v 5015 Radial Ball Bearing Fans | Link | $7.19
Silence/Various | SKR Mini E3 w/ TMC 2209 drivers | Link | $28.81
High Temp | Titanium All-Metal Heat Brake | Link | $11.52
TOTAL: $102.88 US + Tax

Parts already purchased/ bought with printer

Type | Name | Link | Price
---|---|----|----
Reliability/High Temp | OEM Ender 3 Glass Bed | Link | $20
Reliability | Feeler Guage Set | Link | $5
Reliability | 608zz Bearings, using with this(My Remix), this, and this, though I like this design a bit better | Link | $5.98
QoL Improvement | Raspberry Pi 3B w/ Octoprint | Link | $34.46
Silence | Noctua 60mm x 25mm 3-pin fan, goes with this mod | Link | $14.95
TOTAL: $80.39 US + Tax

Future planned upgrades

• Bl Touch (Note: if you have a Pi you don't need a separate ISP to flash a bootloader to the stock Melzi control board)
  
  
• Extruder | Zesty Nimble, Bondtech BMG, or SeeMeCNC EZR
  
  
• Cooling Duct | Either Smooth Fang or Hero Me Gen 3 in PETG/ABS
  
  
• Direct Drive | Kit or Printed (this, this, or this)
  
  
• Electronics relocation enclosure and wiring (need to research this more)
  
  
• Vibration Isolation Feet with Yellow Dot Squash Balls
  
  
• Linear rails (maybe)

Can't say for sure without knowing what size/specs, it will vary by brand as well, but this one I picked at random on Amazon says it's 0.6 ounces most will be around this.

If you use this idler instead of the included one you don't have to remove the feed gear.

https://www.amazon.com/dp/B00G9W20VU/ref=cm_sw_r_cp_api_BLjiybTXV7JFZ

I was able to complete the install in < 10 min

ohhh okay, I was thinking a stationary stand, with a television that could rotate 180 degrees to face either way

what you're talking about would be referred to as a "turntable". You might just have to make it yourself by driving an anchoring piece into the floor, then adding small casters to the corners if need be.

you would want a bearing swivel plate to mount to the floor, base it with wood to the height you need, and then mount your table.

something like this will even hold 1000 pounds and they're used in cabinet making. Which is basically what you are doing.

Aside from the aforementioned glass plate, there are several easy and useful mods. There's many threads going over this actually. Search around.

Get this and make some mods using the bearings. I made the Filament Guide along with a snap-in filament guide for closer to the spool. Both highly recommended.
Also using the bearings, I made a Spool Holder. Not crucial, but might save wear on extruder mechanism.

Get This or something like it and at least install the couplers instead of stock ones. I haven't replaced the tube itself yet. It requires fairly precise cutting but you can get PTFE tube cutting guides and cutters printed from thingiverse.

Get This and install it before glass bed or anything else, except for maybe a bed handle (which you can print from thingiverse. Handle isn't crucial but will help.

I haven't yet but will get:

• a better extruder (all metal or a bmg clone)
  
• a better hot-end (for printing of other stuff, like nylon if I want)
  
  Buy Spare Nozzles, including a hardened steel one if you want to do any amount of printing with wood-grain, metal or glow-in-the-dark material.

This is what I use (for the middle bearing):
https://www.amazon.com/gp/product/B01JKBUR1Q/ref=oh_aui_detailpage_o09_s00?ie=UTF8&psc=1

(for the outside bearings)
https://www.amazon.com/gp/product/B002BBD6X4/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1

I timed my spin to 2mins 20 seconds. Not too bad

> 6804-2RS Sealed Bearing 20x32x7mm (one piece)

http://www.amazon.com/6804-2RS-Sealed-Bearing-20x32x7-Bearings/dp/B002BBGF64

Thanks! The bearing is a full ceramic one I got on Amazon. The design is not mine. It is from Thingiverse, called the Cog Triple Spinner Reddit formatting apparently doesn't agree with mobile sharing links. I fixed it though.

Slightly jerky movement is ok, as long as the final positioning is correct and increments slowly. Say I take 1 full step per photo, and a photo every 10 minutes. With .067deg/step motor+gearbox, it would go about 10 degrees per day total, which is probably fine since it's roughly 300 degrees per month, so if it happened to be a 3 month video, it would go about 2.5 full rotations.

For stiction, you are referring to the stiction of the interface between whatever is being rotated and the base? I have used a stepper before, but it moved much faster and probably had more torque as a result, and used this 'lazy susan'-type turntable device. Hopefully that would be sufficient for this project, and there wouldn't be any step 'skipping'.

(edit: oh unless you mean internal stiction of the gearbox, in which case... I don't know what to do about that.)

I could sync the shutter and movement, but the movement would take little time and the photo is quick (say 1/60 second), so it would be unlikely that the two would trigger simultaneously, although it would be a possibility.

tl;dr for your final question:
Photos every 10 or 20 minutes, rotation on the order of 1-2 rotations a month, leaving some room to fine-tune the rotation rate.

Got a 35$ Amazon gift card from work. There are so many spinners on Amazon I don't know what to get. Suggestions? I was thinking of getting an inexpensive one then replace with a fully ceramic bearing. Thoughts? This is the combination I was thinking (comes to just under 35$)

Spinner

Bearing

I am getting new ones after 500 miles because 1 broke, makes really loud rattling noice
https://www.amazon.com/gp/product/B002BBGF64/ref=oh_aui_detailpage_o01_s00?ie=UTF8&psc=1

Same as already said https://www.amazon.ca/Shuster-6203-2RS-Clearance-Precision/dp/B01NBWOEAB/ref=mp_s_a_1_1?keywords=6203-3%2F4&qid=1565217213&s=gateway&sr=8-1

This is what I use.
http://www.amazon.com/Capacity-Bearing-Turntable-Bearings-VXB/dp/B0045DV04I/ref=sr_1_1?ie=UTF8&qid=1408495735&sr=8-1&keywords=12+lazy+susan+bearing

No, the lowest I see anywhere is a pack of two for bones red but for 1 dollar more (5.50 if you divide 9 by 2) you can get a single all ceramic bearing
I took off my sheilds with a knife. But that is because I bought ones with non-removable shields. Here is a video which apparently shows how to remove the shield

Found some 3/8 Zirconium Oxide Ceramic Ball Bearings on Amazon and decided to go for it. I think it's lighter than SS balls which isn't a problem for me and I just really like how it looks on the turtle

It's on there so tight that I thought this might be the case, but there's a "6200" visible on the bearing, and the 6200 bearings I can find are all separate from a post like so

It's pretty easy to make your own "kit" if you have the BOM and access to Amazon or a site like it. I'm biased because I've always gotten good service from them. Some people have said that I'm biased because they pay me, but I really do try not to recommend places of business that I don't frequent myself.

Anyhow, here are the x upgrade and the y upgrade that I was looking at when I went searching.

Both use 608 bearings and a 10 pack should take care of it and give you several spares for further upgrades or replacements in the future. (want a spool coaster?)

Next you need the GT2 belt and 2 pulleys. Done.

The BOM doesn't say it, but you might need some m3 screws

Edit: Full disclosure: Amazon pays me something like 4% on items that aren't sold by third parties. If everything on this list qualifies and you buy it all I expect to make about a dollar.

Stock large bearings:

[4 PCS] 6903-2RS (17x30x7 mm) Metal Rubber Sealed Ball Bearing (Black) 6903RS https://www.amazon.com/dp/B076BQ9ZB2/ref=cm_sw_r_cp_api_0m5TBbWQWFR5Y

As far as the bearing goes, I've seen them from $10 (vxb via amazon) all the to the $100s. I personally haven't bought any full ceramic ones yet, but I'm waiting on some of the spinners I ordered to arrive so I might be looking to replace them if I'm not content with the ones that come in the unit.

Is that 3rd bearing this bearing? How long does it spin? I was thinking of getting one but I didn't know how long it spins.

Maker Beam starter kit - $112.50 - https://www.amazon.com/MakerBeam-Regular-anodized-including-brackets/dp/B00G3J6GDM

Riuxin Pro knife sharpener kit - $29.95 - https://www.amazon.com/Sharpener-Professional-Sharpening-Fix-angle-III/dp/B015XKSNS2

3" Lazy Susan bearing - $5.95 - https://www.amazon.com/Square-Inch-Susan-Turntable-Bearing/dp/B00ZSQSWTM

-optional-

empty blanks for jig (these are meant to be used as a base for stones, but I just used a glass plate and various grits to flatten them to attach my psa lapping film to) - $28.50/pack of 10 - https://www.amazon.com/Gritomatic-Empty-Blank-for-Stone/dp/B01N0ZINXE

lapping film (I bought 1 sheet of every grit this vendor offers, but I've seen better prices elsewhere) - $5/sheet - https://www.amazon.com/Micron-Lapping-Microfinishing-Aluminum-266Xx1/dp/B071R3S6GS

You can use something like this. I would use a gear motor with a friction drive against the perimeter of the turntable, it's the simplest. One thing though: unless you make very sure the turntable is absolutely level, it may slip or move unexpectedly if the person shifts weight.