Looking For A Source - Idler Pulleys

idbruce

Hello Everyone

As the title staes, I am currently looking for idler pulleys. To be a bit more specific, I am looking for either plastic or metal idler pulleys with ball bearings and two flanges, which are intended to be used with flat timing belts (GT2 - 6mm wide), Preferably having a pulley diameter somewhere near 0.594 in. and flange diameter somewhere near 0.640 in and a bore of 1/4 in. Similar metric pulleys are also welcome. In fact, the goal is to closely match my timing pulleys which have the following specs:

Pitch: 2 mm (GT2)
Belt Width: 6 mm
Bore Size: 5 mm
Pitch Diameter: 11.5 mm
Outside Diameter: 11 mm
Flange Diameter: 16.1 mm
Number of Grooves: 18

Any and all help with this matter will be greatly appreciated.

Bruce

Beau Schwabe

Sounds like something that could be 3D printed. Do you have one in hand to measure from?

T Chap

I use Misumiusa.com for all of this type stuff.

idbruce

Very interesting..... hmmmmmm

Beau - Nope I do not have one in hand

T Chap - I did not think Misumi would offer that so I did not look. I can clearly see that I was wrong.


It appears that I cannot get a ball bearing idler with 18 teeth having the GT2 profile in 6mm width. I must take another look. Thanks for the heads up on where to find these.

Mark_T

You just need 2 flanged ball bearings back-to-back... Teeth not required on an idler.

jdolecki

McMaster Carr

http://www.sdp-si.com

idbruce

No luck so far at Misumi, McMaster, Stock Drive, Small Parts, etc

T Chap

Regarding the flat version, I don't like flat idlers on a timing belt(used on the tooth side), there are noisy and have some additional friction. What I like to use a timing pulley, no hub, with flange, and mount a bearing above and below the pulley in an assembly that supports the pulley both from above and below with equal loading. This eliminates deflection in a high tension application. The toothed pulley is quieter and has less friction than a flat pulley. Problem is, you usually do not find a toothed idle pulley in as many configurations.

If it is only an idler, why not use a tooth count that can be found more easily than the 18? (Unless you do not have the belt length to support a larger diam pulley). An option is to have a custom belt made that is larger to support the larger idler.

http://us.misumi-ec.com/vona2/detail/110302194010/?rid3

Misumi makes custom pulleys for me that are not shown on the website. You can call and talk to a tech, they have done some very custom parts, but custom gets expensive for a one off. They are one of the best companies I have dealt with.

idbruce

Misumi makes custom pulleys for me that are not shown on the website. You can call and talk to a tech, they have done some very custom parts, but custom gets expensive for a one off. They are one of the best companies I have dealt with.

Yea, I have dealt with Misumi in the past and they put out some nice stuff, but like you said, for custom work, it gets expensive.

When it comes to designing anything, I often paint myself into a corner, because I always try to make the smallest footprint possible. As it applies to this situation, these pulleys will be for my new NEMA 17 stepper driven linear actuators, which are intended for a 3D printer prototype. They will be constructed from 2" tubing. I could increase the pulley if I was to increase the tubing size, but that would also increase the weight and load put on another stage, so I am unwilling to do that. The design of the carriage assembly restricts my avilable options. The pulley size stated above actually needs to be obtained, for a nice overall product design.

I also like the idea for a toothed pulley, but I don't want to over complicate the design or drive the cost up too much. If I could accurately bore the stated pulley for a 1/4" sleeve bearing, well I believe that would work pretty decent, but I do not believe I am up to that challenge. If necessary, I will just settle for making my own flat idlers from aluminum stock and sleeve bearings. However, York industries has some nice looking idlers on their tensioners, I think I will nose around the specs to see if I can find something close. I talked them yesterday about their tensioners and they sound reasonably priced, however they did not recommend them for my application, but the pulleys might work. Take a peak at these babies:

http://www.york-ind.com/tensioners/index.htm

EDIT: Actually, they did not recommend the dynamic tensioners but said the static would be fine. LOL Perhaps I had the answer all along.

Lawson

The difference between your pitch diameter and bore is too tight to fit most ball bearings. You can find needle roller bearings that will fit. You'll have to bore out a stock pulley your self. (which is quite feasible on a drill press with a drill and reamer if the pulley has a smooth bore.) SDP-SI.com also stocks micro ball-bearings that would fit, but mind the load-ratings and cost. Another solution would be to use a set of 1/4 inch flanged bearings with the belt running directly on the outside of the bearing.

Marty

T Chap

I have cut smooth and toothed idlers from delrin with a cnc, takes a little effort to get the profile dialed in, but I found a cheap program online that does a nice job of generating a dxf for a gear. I think it was called Gears. 25 bucks. I have other cad programs that can design gears but you can enter a time vortex messing with that stuff. At a certain pulley diameter( as in your case ) there is no room for needle or ball bearings between the inner bore and the tooth. That is why you may need to look at having a shaft through a pulley, and bearings on the top and bottom. This obviously requires a top and bottom plate that is machined to accept the bearings, plug a hinge point.

I have built an idler by machining a top and bottom outer section, with a bearing that presses inside, then put the top and bottom parts together.

idbruce

Okay I believe I have found an answer.

By machining the belt mounting bracket on the carriage assembly to lower the belt mounting height, I can then accommodate a slightly larger timing pulley. York Industries sells a static tensioner with a 24 tooth GT2 idler gear, having a ball bearing. The problem now becomes finding a 24 tooth GT2 gear with a 5mm bore. I don't believe locating this gear should be a problem, but stock drive does not have it in aluminum.

I really like this idea, because I like them tensioners Drill two holes, tap one of them, and install. Easy peasy Japanezey

http://www.york-ind.com/cgi-bin/png_ss3.cgi?ttype=SS&size=3&hhtype=P&btype=LB&pmaterial=A&pprofile=2G&diam=63&pwidth=7.4&pwidthI=&bearingt=B&grooves=24&mclear=&mclearM=4.6&threadst=E&part=SS3LB-2G24A74-B46PE

idbruce

I don't believe locating this gear should be a problem

I take this comment back Locating a 24 tooth GT2 gear with a 5 mm bore is not quite as easy as I thought. The only place that I could find one was Misumi

Alex.Stanfield

You could do fine with a GT2 pulley 8mm bore, 2 (or more) MR84zz bearings (8*4*3), and a M4 bolt.

Alex

frank freedman

Have you looked through the Thomas Registry?

http://www.thomasnet.com/products/idler-pulleys-63872402-1.html

idbruce wrote: »

No luck so far at Misumi, McMaster, Stock Drive, Small Parts, etc

idbruce

Okay here is the shopping list and the current result.....

Stock Drive:
A 6A51M018DF0606 Timing Pulley 18 teeth, 5mm bore, 2mm(GT2) pitch, for a 6mm wide belt

McMaster-Carr:
94035A306 Tight-Tolerance Socket Drive Shoulder Screw, 18-8 Stainless Steel, 5/16" Diameter X 3/4" Long Shoulder, 1/4"-20 Thread
6391K406 SAE 841 Bronze Sleeve Bearing for 5/16" Shaft Diameter, 1/2" OD, 3/4" Length
3367A844 Carbide-Tipped Lathe Tool, Style C-4, 1/4" Shank

Using the carbide lathe tool, I cut a 1/4" wide groove in the Oilite bearing until a diameter of 0.383" was achieved. The belt fits in the groove and the bearing runs on the tight tolerance shoulder screw very smoothly. This assembly has not yet been tested on a working drive, but I imagine it should work just fine.

EDIT: I also slightly champhered the upper portion of the groove to prevent early destruction of the belt.

Alex.Stanfield

This is what I plan to use in my CNC project.

• 1 x GT2 pulley 18 teeth 8mm bore
• 4 x MR84zz bearings (8x4x3)
• 1 x M4 bolt with shoulder 30mm long
• 1 x Self locking nut
• Additional nuts & washers as needed for frame mounting

By stacking several bearings (~$7 for 20 of them) on the bolt and then fastened with the self locking nut you get a nice bearing based idler. Then I slide the GT2 pulley and voila!, your toothed idler is ready.

The only warning is that you should NOT tighten too much the pulley screws as the bearings are easily squeezed and you will feel bumps when turning, maybe it's better to put some screw tighteners (even loctite) and leave the screws out.

Other than that it feels really smooth and it's easily built.

Alex

idbruce

Alex

Just one word of advice.... You really should have a minimal spacer between the bearings. The outer race and inner race are most likely not exactly flush and by bolting them together, you will cause a bind. I know this for a fact, because of numerous the bearings used on my wire straightner. However in my particular case, I did not use spacers, instead I honed the bearing faces until they were flush.

Brian_B

idbruce,

https://www.inventables.com/categories/frame-rail/idlers


Brian

idbruce

Brian

5MM idler pulleys were not the real issue, for my design, I needed idler pulleys that closely matched the pitch diameter of the drive pulley. The belt surface of that idler has a diameter of 0.689" and I needed somewhere around 0.383".