Rotary motion to reversible linear motion

[Brian Rupnow]

I spent a goodly portion of the day modelling all of the components into position and developing wooden bracketry (pale green), pulleys (yellow), and drive belts (black). I also received my package of 50 rubber o-rings from McMaster Carr. Right now I'm rooting thru all my metal supplies to see if I have enough material to make all the pulleys from.

 

[Brian Rupnow]

YES!!!---I've got enough material to build all of my pulleys for this project. This afternoon I installed one of my new 1/4" cross section rubber o-rings on my driven shaft, and the results are less than stellar. This is probably because I am using solid bronze or brass pillow blocks on the driven shaft, and I may have to make new pillow block bearings that actually hold ball bearings to avoid the friction I am getting. Fortunately I have a couple of 5/16" ball bearings that I have recovered from an old project.

 

[Brian Rupnow]

Today I made up the first of my many pulleys, this one fitting on the engine. I make the grooves the same width as the o-ring that I am using for drive belts. I made up a 1/16"wide knurling wheel a few years ago, and I use it to knurl the bottom of the o-ring slot so that the pulleys don't slip when driving the o-ring. I would have liked to use timing belt style pulleys and belts for this job, but they cost way too much. The last time I bought a timing belt and two small (about 2" dia.) pulleys, it cost me more than $150 dollars.

 

[Brian Rupnow]

Just call me the "Pulley King" of Carson Road. All my pulleys are finished except for the output from the clutch. One on the engine, two on the gear reducer and the input pulley for the clutch. I've used up every scrap of aluminum round stock that I had. I actually found a scrap of aluminum plate to make the last pulley from, but I'm too tuckered to do anymore today. I'm amazed that I've made up all of these pulleys from short pieces of stock I found laying around my shop.

 

[Brian Rupnow]

Yeah!!! All of the pulleys are finished.--And best thing of all, I didn't have to buy any material. There isn't a scrap of round aluminum left anywhere in my shop, but the pulleys are finished. The engine, clutch, and gear reducer are "posed" for the picture---Those are not the right o-rings shown, but they are in the correct relationship to everything.

 

[Brian Rupnow]

I found something out today that I never knew. There are some situations where I would like to use a ball bearing on a shaft, but the outer diameter of a ball bearing is too large for my application. I have always been under the impression that needle bearings which come with the outer race but no inner race must use a purchased inner race, (which again makes the outside diameter too large) or else they must run on a hardened shaft to keep from galling the shaft material. I spoke with a rep for Koyo bearings today, and they make a needle bearing with an outer race that needs no inner race nor a hardened shaft. The rollers run directly on a 1045 steel shaft that is not hardened and they will not gall it. I will go over to Canadian Bearings on Monday and find out more about this. If it's really true, it will get me out of a bind. The outer diameter of a 3/8" ball bearing is 0.875". The outer diameter of a 3/8" needle bearing is 9/16". This is a B68 Koyo bearing.

 

[Brian Rupnow]

I foresee lots of woodwork in the very near future. Today was buying wood, cutting to size, and laying out screw holes. I still don't have the wood I need for the risers between the top and bottom plates, but I will check my own stash this afternoon and buy a piece if I need to. I don't mind working with wood---don't do a lot of it and when I do, it's mostly sander and tablesaw work.

 

[Vietti]

I found something out today that I never knew. There are some situations where I would like to use a ball bearing on a shaft, but the outer diameter of a ball bearing is too large for my application. I have always been under the impression that needle bearings which come with the outer race but no inner race must use a purchased inner race, (which again makes the outside diameter too large) or else they must run on a hardened shaft to keep from galling the shaft material. I spoke with a rep for Koyo bearings today, and they make a needle bearing with an outer race that needs no inner race nor a hardened shaft. The rollers run directly on a 1045 steel shaft that is not hardened and they will not gall it. I will go over to Canadian Bearings on Monday and find out more about this. If it's really true, it will get me out of a bind. The outer diameter of a 3/8" ball bearing is 0.875". The outer diameter of a 3/8" needle bearing is 9/16". This is a B68 Koyo bearing.

Good to know. Amazon has them for $5.85- unfortunately us dollars and don't know if Amazon services Canada

 

[Sparky_SC]

I found something out today that I never knew. There are some situations where I would like to use a ball bearing on a shaft, but the outer diameter of a ball bearing is too large for my application. I have always been under the impression that needle bearings which come with the outer race but no inner race must use a purchased inner race, (which again makes the outside diameter too large) or else they must run on a hardened shaft to keep from galling the shaft material. I spoke with a rep for Koyo bearings today, and they make a needle bearing with an outer race that needs no inner race nor a hardened shaft. The rollers run directly on a 1045 steel shaft that is not hardened and they will not gall it. I will go over to Canadian Bearings on Monday and find out more about this. If it's really true, it will get me out of a bind. The outer diameter of a 3/8" ball bearing is 0.875". The outer diameter of a 3/8" needle bearing is 9/16". This is a B68 Koyo bearing.

A B68 is nothing special as needle bearings go. It is a full compliment type caged bearing which equates to higher loads. A extremely common bearing.

Here is the Koyo catalog. Look at section 5.1 for specifications on shaft requirements. This includes the "B" series as listed in the first part of the catalog.
A shaft hardness of HRC 58 is recommended as well as preferred steel alloys. http://nocinternational.com/pdfs/koyo-b2003e-en.pdfn

The housing the bearing presses into can be mild steel or even aluminum as long as it meets roundness requirements.

The info the "rep" for Koyo gave your contradicts their published specs. No doubt Canadian Bearings will confirm this for you. You being a engineer can also interpret the specs yourself as well.

(One of my first jobs out of school was for a large bearing distributor. I went to torrington factory school as well as others. Not much has changed)

 

[Model T Ford]

A B68 is nothing special as needle bearings go. It is a full compliment type caged bearing which equates to higher loads. A extremely common bearing.

Here is the Koyo catalog. Look at section 5.1 for specifications on shaft requirements. This includes the "B" series as listed in the first part of the catalog.
A shaft hardness of HRC 58 is recommended as well as preferred steel alloys. http://nocinternational.com/pdfs/koyo-b2003e-en.pdfn

The housing the bearing presses into can be mild steel or even aluminum as long as it meets roundness requirements.

The info the "rep" for Koyo gave your contradicts their published specs. No doubt Canadian Bearings will confirm this for you. You being a engineer can also interpret the specs yourself as well.

(One of my first jobs out of school was for a large bearing distributor. I went to torrington factory school as well as others. Not much has changed)

Not quite sure about the info contradicting things. If you look on page 12 of the manual in the bottom right corner there is a graph showing how to apply a correction factor for load if the hardness of a shaft on which the rollers are running is less than HRC60. It may be that the sort of forces applied to these bearings in model engines is relatively low and so it would be quite OK to use them directly on a non hardened shaft?