Grinder build Help

[timos-]

Hello All,

Getting close to finishing my Grinder build.

I am still having a hard time picturing the tracking wheel mechanism and the specs on the aluminum wheels.

This is the basic grinder.

Here we have the aluminum idler wheels. I am wondering if these idler wheels have counter bores for some sealed bearings to be pressed in? If so it seems that the bearings will be spinning around a bolt as opposed to a shaft? Or are these Lag bolt types?

The real trouble for me is the tracking mechanism.

I cannot see how the roller mount pivot will allow any movement for the bolt to be turned.

I am going crazy trying to wrap my head around this. Am i over thinking it?

Much thanks to any thoughts shared

Hope everyone is having a great holiday week


-Tim Johnson

 

[Jesse Latham]

Your drawing shows the tracking wheel mounting bolt extending into the tracking support arm. Correctly made it will end in the roller mount block, allowing the tracking wheel to move up and down. Take a look at what Polar Bear Forge makes. You probably will not be able to buy and fab the metal for what he charges. Jess

http://www.polarbearforge.com/grinder_kit_breakdown.html

 

[12345678910]

I think this should help you understand and visualize most of what you want to do.

http://www.dfoggknives.com/PDF/GrinderPlans.pdf

Here we have the aluminum idler wheels. I am wondering if these idler wheels have counter bores for some sealed bearings to be pressed in? If so it seems that the bearings will be spinning around a bolt as opposed to a shaft? Or are these Lag bolt types?

The drive wheel is solid with a keyway, all other wheels have bearings pressed in.

The NWG and KMG designs use a 1/2" hex head cap screw
a Lag screw is a wood screw

Yes this is a wheel, 2dia and 2 width is fine, but the pocket diameter and depth will depend on the bearings you use.

Maybe those dimensions match a bearing, but the most common is an R8-2RS
http://www.fastenal.com/web/products/detail.ex?sku=0474494


Tracking
If you study the photos and drawings in the plans, it should be really clear.
The tracking wheel is mounted on a stud which hinges up and down.
The tracking screw handle just pushes on the back of the hinge.
It's not one screw all the way between the two blocks.

 

[timos-]

Thank you Jesse and 12345678910 for clearing this up for me! I get it now!

Also wondering if anyone has tried using Acetal (Delrin) for idlers as opposed to aluminum?

 

[12345678910]

Thank you Jesse and 12345678910 for clearing this up for me! I get it now!

Also wondering if anyone has tried using Acetal (Delrin) for idlers as opposed to aluminium?

I'm not familiar with Delrin, but the white UHMW works.

 

[timos-]

I do have TONS of UHMW-PE I could use. This stuff is pretty soft but machines great and is cheap. Im also wondering if Nylon would be ok as it is harder more like aluminum. Ive ordered some of those bearings from fastenal and will press em in to some UHMW and see how it works out.

Ive ordered a tracking wheel and hardware from USAKnifemaker and am looking to machine the drivewheel from 6061-t6 aluminum later today.

Im also wondering about the bearing mounts for the drive shaft. I have drilled and tapped the support plates for 1/4 20 screws but notice the 4 bolt mounts Ive got from Beaumont have 7/16s diameter holes. Wondering if I should machine some small sleeve bearings to fill the gap or is there a better way?

 

[PT Doc]

Im also wondering about the bearing mounts for the drive shaft. I have drilled and tapped the support plates for 1/4 20 screws but notice the 4 bolt mounts Ive got from Beaumont have 7/16s diameter holes. Wondering if I should machine some small sleeve bearings to fill the gap or is there a better way?

This play could allow for adjustment since the motor shaft does best without sideloading but that is quite a bit of play. Try it and see and you could always add a sleeve or just d&t the right size hole.

 

[timos-]

Hi all,

The grinder is coming along. I am concerned about the tension arm being a bit wobly. There is no play in the joint but the arm is still able to move side to side a bit. Is this normal for a KMG style? I am hoping the belt tension on the tracking wheel will keep the arm from vibrating side to side. I am considering milling an arc support for the handle end of the arm but hope this wont be necessary. BTW ive used 3/4 steel for the arm and arm support.


-Tim

 

[fumbler]

If there's no play in the joint then where's the movement coming from?

You'll probably be fine. I have a KMG and without tension you can feel a tiny bit of lateral movement. It goes away once there's a belt on.

 

[12345678910]

Hi all,

The grinder is coming along. I am concerned about the tension arm being a bit wobly. There is no play in the joint but the arm is still able to move side to side a bit. Is this normal for a KMG style? I am hoping the belt tension on the tracking wheel will keep the arm from vibrating side to side. I am considering milling an arc support for the handle end of the arm but hope this wont be necessary. BTW ive used 3/4 steel for the arm and arm support.


-Tim

This joint should be a better fit than just an oversized drilled hole with a screw through.
I feel the same way about the tracking pivot too.

Shoulder bolts and a reamed hole are the way I would do it.

 

[timos-]

Thanks again guys.

That is where the play is; the bolt hole. .005 is too much. I was so concerned with the elbow I forgot about the bolt