Reddit mentions: The best ball bearings

It honestly depends on your budget, how much are you willing to spend?

Here is a great list of prep and upgrades you can do to bring success to your prints:

-Get Vibration Dampners: I can not express how much joy these things have brought many users. The make your machine quiet and greatly decrease ringing in your prints since they ABSORB the vibration coming from your stepper motors. You really only need Two of these for the X and Y axis however you can get another two for the Z-axis drives if you plan on doing a lot of z-hopping.

-BUY FILAMENT IN ADVANCE: get some PLA/ABS/PETG or whatever you want to try printing with. The filament you get with the printer for the most part is garbage HOWEVER I recommend dialing in those settings first then throwing on some nice filament, it'll feel soooo nice. Some commonly accepted/appreciated brands are: eSun PLA+, Hatchbox, Solutech and more

-Get a PEI sheet: Seems like you mentioned this in your post but PEI sheets eliminate the use of gluesticks/tape/hairspray and provide excelent adhesion while making it easy to remove the part after it's cool. This things like to be hot though so increase your bed temp a little at first

-Buy New Fans: The stock hotend/power unit fans are Loud, Noisy and Inefficient. I recommend getting 1 new conrol box fan, 1 new hot end fan and 1 new part blower fan.
You will need 1 40mm fan, 1 50mm fan and a Blower fan or another 40/50mm fan depending on if you print a new hot end mount like a fang.

-Tighten every screw on the printer: You would be surprised how many screws initially are lose either from prior testing or such. Also make sure to test your belt tensions on your printer whne you get it. You want everything tight BUT NOT TOO TIGHT. Give it a snug fit then let it be. Also make sure your belts are 'pluckable' like a guitar string but not tought

-Get some bearings: You may want to get a few ball bearings for when you print out a new filament holder, the stock filament holder is terrible

-Buy some fasteners: M3 bolts and nuts are commonly used on the CR-10S having spares or additional fasteners for adding on parts/printed components to your printer is awesome to have on hand

-Replace the Hotend: This can get a bit frustrating but it can be worth it. If you want you can replace the hotend with something like a volcano or an all metal hot end to print at higher temperatures. With this you can also add on autoleveling if you have the correct mount printed

-Octoprint: I am not very familiar with octoprint since I don't use it myself however I know it can run on a CR-10S. If you want look into how to install octoprint on stock firmware, I know it's pretty easy to use a raspberrypi to remote into your printer as well using octoprint.

-Squash Feet: Replacing your stock machine 'feet' with squash balls or squishy gold balls can also help absorb vibrations from your machine to your table or where it is located. This helps a bit with part quality but it's mostly to reduce the noise carried through your furniture.

-Solder on connectors: If you want you can get some pin connectors to make your fans/electronics easy to switch out depending on your material you are printing, maybe you need a strong part fan or maybe you need a weaker one. It is easy to swap out if it's using a 4pin connector.

-Make an Enclosure: What could be nicer for your printer than a stable environment. Making an enclosure for your printer can help if you live in a rough climate area or if you want to reduce the noise as well.

-Get some Handtools: I'm not sure if you have any or not but some great tools to have are a screwdriver, hexwrenches and a soldering iron depending on how much work you want to be doing on your printer.

For convenience I've added some of the parts mentioned via an Amazon link for prices. I'm not saying buy these things exactly they are just a starting point for reference:

Nima Vibration Dampners:https://www.amazon.com/Stepper-Rubber-Vibration-Dampers-Printer/dp/B073FRZTDX/

40mm Fan (Noctua Brand): https://www.amazon.com/Noctua-NF-A4x20-FLX-premium-quality-quiet/dp/B072JK9GX6/

Blower Fan (Part Fans):https://www.amazon.com/SoundOriginal-Humidifier-Aromatherapy-Appliances-Replacement/dp/B071WMHNG5/

PEI Sheet/Printer Surface:https://www.amazon.com/CCTREE-Printer-Surface-Creality-300x300mm/dp/B07543KHCT/

Squash Feet: https://www.amazon.com/PrideSports-Practice-Balls-Count-Yellow/dp/B00466W9X0/

M3 Bolts/Nuts:https://www.amazon.com/280Pcs-Grade12-9-Socket-Assortment-Storage/dp/B0742DDLQ1/

Raspberry Pi 3 for Octoprint: https://www.amazon.com/Raspberry-Pi-RASPBERRYPI3-MODB-1GB-Model-Motherboard/dp/B01CD5VC92/

Ball Bearings: https://www.amazon.com/625ZZ-Shielded-Groove-Precision-Bearings/dp/B01LWMT95S/

Hope this helps, have fun tinkering!

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'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)

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.

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 :)

I believe it was an 18" pine round board from Lowes. Pine is a bit of a softer wood, but I got it because it was cheap, just about the right size, and I had a gift card with enough left on it to cover the purchase. I reused my existing hardware and mounted the uprights perpendicular to the grain and countersunk the holes, using washers to prevent and chances of the wood splitting.

For the azimuth bearing itself, I've tried a few different things:

Lazy susan sometimes works, sometimes doesn't
https://www.amazon.com/gp/product/B071CPFGJT

Inside this bearing raceway is a plastic spacer that separates the bearings-- I left this in there, as it added just the right amount of friction to prevent the base from spinning too freely. On my XT10 rebuild, it happened to be perfect and I needed no modifications to get the right balance of movement and friction. It was a one and done type of deal.

On a separate dob base rebuild, using the same type and size bearing, it was spinning too freely and I needed to add friction-- sometimes a couple folded cotton socks wedged in between the boards would work great, but later became unbound...then I tried felt pads that rode against the wood...which sometimes worked, other times too much friction... results were inconsistent and I wound up ditching the lazy susan on that build, opting to use furniture sliders against a 99 cent vinyl record from a thrift store. The texture on the vinyl record provided a proper amount of friction to interface with the furniture sliders. Not the best movement, but served its purpose.

Quite a few ways to skin a cat and if I were to do it again, I'd try it with FRP wallboard and virgin teflon pads:

https://www.homedepot.com/p/Glasliner-4-ft-x-8-ft-White-090-FRP-Wall-Board-MFTF12IXA480009600/100389836

My ES truss dobs use this exact material against virgin teflon and it performs very well. I have no problems tracking at high power. This is one of the tried and true combinations among ATMers, and you should be able to find someone who can sell a 16" x 16" cut, as hardware stores usually only sell it in huge 4'x8' sheets. I'll probably pick up a huge sheet of this to play around with.

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'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.

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.

vxb.com has cheaper bearings, better quality control, and faster shipping. They even give you the better silicone nitride balls instead of the zirconium balls in your post...

Amazon: https://www.amazon.com/gp/aw/d/B002BBQDW0/ref=pd_aw_sim_sbs_328_1?ie=UTF8&psc=1&refRID=47JQJW50MCFDYSRDPSK3

VXB: http://www.vxb.com/608-Full-Ceramic-8mm-x-22mm-x-7mm-Miniature-p/608zr02-zr02-ptfe.htm

The vxb website shows zirconium balls but when I bought it I was given the silicone balls which is false advertising, but in a good way, because silicone is better.

If you have a good relationship with your LBS and they'll sell what you need from their bulk supply, that is awesome. My LBS experience is that they carried single-serve packs that were pretty pricey.

Here's an amazon link for 5/32. Check the "other people buy" list for different sizes and quantities.

https://www.amazon.com/gp/aw/d/B0012LFT7U

https://www.amazon.com/Rubber-Sealed-Bearings-8x16x5-688-2RS/product-reviews/B00F4BZ8XE

Just make sure you take off the bearing every time you clean the brush and get the hair out of it. That maintenance with the sealed bearing insures there will never be a problem. Really the only flaw of this cleaning robot imo. It's such a good cleaner that ive forgiven it of this short coming.

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

>Female bolts are superior in every way to track nuts.

True but you would never notice the difference while riding

>Different aluminium alloys have different properties

Mack hubs use 7075 T6, thats pretty common for higher end components. I couldn't find out what formulas are made of but it's probably 6061 which is slightly less dense and a little heavier. You wouldn't notice the difference while riding though.

>Bearings can be round to a greater degree than others

Yea but Mack hubs use 6 dollar chinese bearings that can be found here. These are nearly identical to the bearings found in all other sealed track hubs.


This is why I hate boutique bikes, you pay so much because it was "handmade", not because its a vastly superior product.

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.

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

Sounds like what you want is a standard ball bearing, like this, only you need to match the bearing's inner diameter with the diameter of the gear. You can always glue it in place if the bearing is slightly larger than the gear. Then, wedge/glue the outer ring of the bearing into a circular hole wherever it's supposed to go, and the gear will rotate freely without moving laterally.

Haha, I've got one of those you can buy off me too. Richland Rick?

Make sure the inside of the sprocket carrier doesn't have that 'lip'. I'd replace the bearing with a sealed, grooved unit, cheap upgrade, with a spare. These ones are japanese (not chinese), and fit without a hitch. With 24K miles, my OEM bearing was showing signs of oxidation (rust colored goop). Use the OEM bearing to tap in the new one.

http://www.amazon.com/gp/product/B002BBM6J4/ref=oh_aui_detailpage_o00_s00?ie=UTF8&psc=1

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_BLjiybTXV7JFZ

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_nMjiybB65P122


I bought the two items above. You keep the current extruder gear, install the extruder minus the new gear and replace the bearing on the new extruder with one of the flanged ones from amazon. I think I installed flange down. It only works in one orientation. This is currently working great and much more sturdy and with better, adjustable pressure on the filament.

It sounds like yours is fine. Mine was easy to move before I tightened it. I couldn't find any numbers for proper torque. I had already ordered bearings: this for the discontinued one, and this for the other one.

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

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.

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.

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.

Well, they'll work, but they'll probably spin for 10 seconds max. If you're getting a 3d printer spinner, you can get those cheap bearings for the edge holes and then get 1 good center bearing. I'd go with this one. May be more than you wanted to pay but off brand bearings won't spin long at all

Thanks, I used regular skate bearings. https://www.amazon.com/gp/product/B07C6FL8TW/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

You may love him but he does not reciprocate the feeling.

Amazon has 10 bearings from vxb for 5.60 including shipping. They are shielded but you can remove them and clean out the grease so it spins longer. From here it depends on what body you want. If you want an all metal one I highly suggest FlyAwayToys. But when you do this, you have to get the center button. If you get them from FlyAwayToys it adds up to the cost of buying a whole spinner including a bearing from him. Might as well buy a pre-made one.

If you want to make your own, it will not be perfectly balanced but it is cheaper and you get multiple spinners that you build/customize. You can get nuts (cheap) or ball bearings from a hardware store, attach them with jb weld. I preferred knurled nuts/bolts as the center button. Cost about $3 for 3 sets. BUT they break sometimes when dropped so prepare a few of them as backups. File off the jb weld with a file or sandpaper and rebuild it. 56 cents a bearing if you get the bundle.

Or $9.95 with free shipping on Amazon.

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.

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

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.

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

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

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

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

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.

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

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

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

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

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