SKU: 76108446997

Pololu Multi-Hub Wheel w/Inserts for 3mm and 4mm Shafts - 80x10mm, Black, 2-Pack Pololu 3690

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Description

Pololu Multi-Hub Wheel w/Inserts for 3mm and 4mm Shafts - 80x10mm, Black, 2-Pack Pololu 3690These versatile black plastic wheels have silicone tires and measure 80 mm (3. 15) in diameter. What makes them special is the included set of interchangeable collets that can be inserted into the wheel to firmly grab four different shaft types: 3mm D, 3mm round, 4mm D, and 4mm round. The collet inserts start with a comfortably loose fit on their intended shafts, and unlike simple press fit wheels, their grip on the shaft gets progressively tighter as

These versatile black plastic wheels have silicone tires and measure 80 mm (3.15″) in diameter. What makes them special is the included set of interchangeable collets that can be inserted into the wheel to firmly grab four different shaft types: 3mm D, 3mm round, 4mm D, and 4mm round. The collet inserts start with a comfortably loose fit on their intended shafts, and unlike simple press-fit wheels, their grip on the shaft gets progressively tighter as they are compressed into the wheel disc, reducing the chances that the shaft will be able to slip within the wheel. This product is a pair of wheels.


Overview

These versatile wheels use interchangeable collets to tightly grab a variety of different common motor shafts, including the 3mm D-shafts on our micro metal gearmotors and mini plastic gearmotors and the 4mm D-shafts on our 20D metal gearmotors and 25D metal gearmotors. The wheels are 80 mm in diameter with 10 mm wide silicone tires, and they are available in black or white.

Black 80×10mm Pololu Multi-Hub Wheel installed on a 4mm D-shaft.

White 80×10mm Pololu Multi-Hub Wheel installed on a 3mm D-shaft.

80×10mm Pololu Multi-Hub Wheel installed on the 4mm D-shaft of a 20D metal gearmotor.

80×10mm Pololu Multi-Hub Wheel installed on the 3mm D-shaft of a micro metal gearmotor.

Four different collet inserts are included per wheel, allowing the wheel to work with four different shaft types: 3mm D, 3mm round, 4mm D, and 4mm round. The collet inserts slide easily onto their intended shafts and then clamp down as they are compressed into the wheel disc, resulting in a fit that is much tighter than can be achieved with similar press-fit wheels. The combined thickness of the collet and collet plate is approximately 6 mm, so we recommend you use this wheel with motors that have shafts that are at least 7.5 mm long. See the dimension diagram (384k pdf) for more information.

 

Pololu Multi-Hub Wheel collet inserts: 3mm round, 3mm D, 4mm round, and 4mm D.

Details for item #3690

This product is a pair of black 80×10mm wheels, and it consists of two sets of the following parts:

 

Pololu Multi-Hub Wheel w/Inserts for 3mm and 4mm Shafts – 80×10mm, Black, 2-pack.

  • silicone tire
  • black ABS wheel disc
  • four black ABS collet inserts:
    • collet for 3mm D-shafts
    • collet for 3mm round shafts
    • collet for 4mm D-shafts
    • collet for 4mm round shafts
  • threaded metal collet plate
  • three 7mm-long M3 screws

Using the wheel

 

 

Installing the Pololu Multi-Hub Wheel on a motor shaft.

  1. Insert the motor shaft through the hole in the middle of the collet plate, making sure that the protrusions around the three threaded holes are facing out, away from the motor. Warning: these protrusions can be sharp!
  2. Slide the appropriate collet onto the motor shaft, making sure that the embossed digit (i.e. the “3” or “4”) is facing out, away from the motor.
  3. Slide the wheel on to the motor shaft with the embossed Pololu logo facing out, away from the motor, and press it onto the collet firmly, which will cause the collet to start squeezing down on the shaft. If you have the collet or wheel backward, the collet will not fit into the hole in the wheel.
  4. Insert three M3 screws through every other hole in the wheel and start screwing them into the threaded holes in the collet plate. Tighten each screw a little at a time so the wheel is pulled onto the collet evenly. For typical shafts, you will be able to tighten until the collet plate is almost flush with the back of the wheel, and the front of the collet is almost flush with the front of the wheel. If your shaft is a little larger than nominal, the collet might not press as far into the wheel, and if your shaft is a little smaller than nominal, you can insert something like a small washer between the collet plate and the collet to let it push the collet even farther into the wheel (i.e. past flush). Be careful not to over-tighten the screws as this can strip the threading on the collet plate.

Note that it is possible to assemble the wheels with a little wobble, but if that is a concern in your application, you can adjust how you tighten the three screws to get it as lined up as you like. Alternatively, you can often also fix a wobble just by pushing hard on the rim of the wheel at place where it’s most out of alignment.

The hole spacing on these wheels also works with our larger Universal Mounting Hubs (6 mm diameter and up), which can be used to adapt these wheels to motors with larger shafts, like our 37D metal gearmotor shown here:

If you get an M3 version of the universal mounting hub, you can use the 7 mm M3 screws that are included with the wheel to mount them together. However, please note that those screws will only go about 2 mm into the universal mounting hub, so you might consider getting longer screws (like 10 mm M3) for a more secure setup.

Specifications

Parameter Value
Size 80 × 10 mm
Weight 23 g
Shaft type 3mm D, 3mm round, 4mm D, 4mm round
Color black

Resources

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SKU: 76108446997

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Tiffany F.
Natrona Heights, US
★★★★★ 5
Very Comfortable - Love this!
Size: Full, Style: 1 Green
So far, so good! I am going on my first night trying this mattress topper out. It feels very comfortable and definitely is fluffy, but not too fluffy. I did not "fluff it out" or put it in the dryer to fluff it out quicker, so perhaps it still needs some time to fluff out some more. It was very easy to place on my mattress. I didn't have to fight with it as I normally would when fitting a sheet to my mattress. I love that it stretches over the sides of the mattress to hold it in place. The bamboo truly gives a cooler effect, which will be very helpful in the summer time. I used a microfiber mattress topper prior to ordering this topper. So far, the comparison is that this one appears to be well made and durable, unlike the microfiber one I had before that changes color as it gets old and dirty and is impossible to clean. The old one actually ripped and would constantly move. I am excited to see how well this one holds up over time. I had no trouble placing a fitted sheet over this mattress topper. I love that this one is machine washable and is able to be placed in the drier. It feels very nice on my legs and is comfortable for my back as well. The padding doesn't feel thick or bulky but definitely adds a softness that is super comfortable. It's too soon to tell if it's water resistant as I haven't tested that feature out yet. I placed it over an old, springy mattress and it truly feels like I have a whole new mattress. Time will tell how well this product does the job and I will update this review if I end up having any issues with it.
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Reviewed in the United States on May 25, 2026
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Aurihazuma
West Palm Beach, US
★★★★★ 5
OMGAAAAAWD!!! HEAVEN!
Size: Full, Style: 1 Green, Size: Full, Style: 1 Green
All I can say is OMGAWD!!! Thank You~!~!! We got a new mattress after the previous "The Cloud" Serta pillow top (I'll never have another one) lasted for less than 8 years and I totally despised not being able to flip it models failed.. The new model is also a hybrid mattress, but is flippable and was just a bit too firm. I was feeling progressively more and more uncomfortable as the nights wore on, and with my serious back problems.. this just wouldn't do.. So I began searching "Our Beloved Amazon - heh" for an alternative, and after quite some time and research finally landed on this wonderful topper. It's like sleeping on top of well stuffed Ida Down on top of piles of silk. So very comfortable and my back pain is virtually completely gone now -such a relief! Be sure you follow the instructions on care and initial setup. You Do have to let it fluff out because of the vacuum packing (it wasn't really heavy btw). Mine decompacted fine, but I still want to run it through the dryer when we next venture to the laundromat. Shake it a little here and there when you take it out and at least let it sit for a few hours. It was just as easy to put on the bed as a regular mattress protector, and I also put my regular protector on top of it for added security and waterproofing. The materials feel like they are of good quality.. Viscose is also called Rayon and can be made from a number of different materials, so take good care of it and follow the washing instructions carefully. Delicate only, and cool only, and use only a horizontal washer that does not have a central agitator or you will tear it up. Only dry on low temperatures (preferably in a very larger laundromat dryer so it has plenty of room to loosely toss about. Drying it in the sun is alright as well, but it won't fluff like you want it to. I recommend using a waterproof and bug proof protector on top of this just to be sure you take care of it properly. Now I want to buy one for both my Mother and my Aunt HAHAHHA! TG it is in my price range.. barely. (Addendum: I have run it through the big dryer at the laundromat.. The dryer was cold so I gave it a quick warm on medium for anout 2 minutes and then tumbled on low for quite some time. The topper was fully ready in about 25 minutes, but I decided to elt it go on low while I did the rest of my laundry. It did perfectly and is just like the manufacturer photos.. I was so tired when I arrived home that I just flaked out on top of everything.. It was so comfortable that I was out liek a light in very short order and slept beautifully. I can attest that if you use this below your sheets instead of covering it with an additional mattress protector, that it does have better cooling effect. I will of course keep my waterproof/bugproof protector on top just for safety. The cat is nutz about the new topper as well.) Namaste.
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Reviewed in the United States on August 6, 2025
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Kathleen Kowalski
Phoenix, US
★★★★★ 4
Not like the pictures but well worth the money
Size: Queen, Style: 1 Green
4 stars because it is not nearly as padded as the descriptions and images make it seem. The filling flattens easily and doesn’t provide any support. That being said it does make my bed more comfortable and soft and has improved my sleep quality. I have a 12 in soft/medium firm memory foam mattress that was wonderful for the last +2 years till my back surgery ~6 months ago. Since then my joints ached when trying to sleep and when waking, my back would be all out of place and achey, and I was untested. Since buying this topper these issues have improved by 80% or more. It is a great addition to my bed and I don’t regret buying it.
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Reviewed in the United States on May 18, 2026
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Chelsey Yarno
Lowell, US
★★★★★ 5
Pleasantly surprised!
Size: Queen, Style: 2 Dark Gray
I had been searching for a quality mattress topper in hopes of extending the life of our mattress. I compared a few options and kept coming back to this one. I have to admit I was skeptical because the price point was lower than many options. This topper is SO comfortable and soft! I left it laying out for a couple hours and then followed the instructions to put it in the dryer. Worked like a charm. I’ve been going through issues with hip pain and this has made a difference in my sleep and I’m waking up in less pain. So happy I tried this out. The padding is so comfortable and fit on the mattress using the same sheet we had.
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Reviewed in the United States on May 17, 2026
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KeepsGettingBetter
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★★★★★ 5
So perfectly soft
Size: King, Style: 2 Dark Gray
My husband was complaining about the mattress, and wants to spend a lot of money on a new one like the ones at the Waldorf. I asked him to give me a chance to try to fix it first. Watched youtube videos about hotel style beds, and landed on the need for a mattress topper. This one is so... very... comfortable. I thought the grid pattern would bother me, but nope. You don't realize how much heat you soak up from your mattress until you get a nice airy layer in between. I almost completely stopped sweating at night, and he's stopped complaining about hurting as much. This is another of those items that I'm scared of washing too much, but it's held up with care and caution. If it starts to get a bit too squished, I just fluff it in the dryer and the padding poofs right back up. The sides are deep and my mattress sinks right into the pocket with no pulling. I have bad back pain and I am certain this has been helping support my back a bit better, so I wake up more refreshed. I'm sorta popping out of bed like I used to years ago. He still plans on a new mattress, but this has saved us money, for now, and when we get the new one, this will layer on top like a dream. I'm glad I took the chance on this, it has really improved our rest, and that's so important.
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Reviewed in the United States on May 16, 2026

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