The Bandsaw mill I am slowly renovating used to have a pair of roller guides at the pre and post cutting sides of the blade but the previous owner replaced these with wooden blocks because the bearings in the roller guides kept seizing up. The use of wooden blocks clearly adds significant friction to the system which I want to minimize.
The bearings are sealed but there is lots of water from the blade cooling spray plus sawdust flying around and without regular greasing it's no wonder they seized. Bandsaw manufacturers recommend greasing these bearings twice a day but these bearings are located inside the rollers so it's impractical to grease them on a regular basis.
I want to have a go at reinstating the rollers and adding grease ducts and nipples to the rollers
The cross section of the original rollers is shown on the left of the picture.
The rollers are 50m diameter case hardened steel with a small shoulder on one side and 3 V grooves on the case hardened surface.
There are 3 sealed ball bearings stacked inside the roller and a 12 mm bolt passes through the bearings and holds the roller to the mill frame
This is what I am considering.
Removing the middle bearing completely - see picture on the right.
B1 is moved 3.5mm outwards and together with the removed middle bearing this creates a grease reservoir in the middle of the roller. A spacer will hold the internal bearings apart.
To get grease into the reservoir I thought of drilling a vertical hole from the outer rolling surface of the roller to the reservoir, and a second horizontal hole from the front face of the roller to intersect with the vertical hole.
A grease nipple would then be added to the outside of the horizontal hole.
Once everything is aligned I would plug the top part of the vertical hole with a brass plug so that when grease is applied the grease would flow in the direction of the red arrows. As you can see to get grease to flow thru B2 I will need to drill some small escape holes through to the front of the roller.
Now the question.
Should I drill the vertical hole though the middle of one of the grooves (and have to deal with the vagaries of starting to drill a hole in a groove) as in OPTION A on the diagram
OR
Drill the hole starting on the outer shell of the roller as in OPTION B?
At full load speed the bearings are doing around 7000 rpm.
The bearings are sealed but there is lots of water from the blade cooling spray plus sawdust flying around and without regular greasing it's no wonder they seized. Bandsaw manufacturers recommend greasing these bearings twice a day but these bearings are located inside the rollers so it's impractical to grease them on a regular basis.
I want to have a go at reinstating the rollers and adding grease ducts and nipples to the rollers
The cross section of the original rollers is shown on the left of the picture.
The rollers are 50m diameter case hardened steel with a small shoulder on one side and 3 V grooves on the case hardened surface.
There are 3 sealed ball bearings stacked inside the roller and a 12 mm bolt passes through the bearings and holds the roller to the mill frame
This is what I am considering.
Removing the middle bearing completely - see picture on the right.
B1 is moved 3.5mm outwards and together with the removed middle bearing this creates a grease reservoir in the middle of the roller. A spacer will hold the internal bearings apart.
To get grease into the reservoir I thought of drilling a vertical hole from the outer rolling surface of the roller to the reservoir, and a second horizontal hole from the front face of the roller to intersect with the vertical hole.
A grease nipple would then be added to the outside of the horizontal hole.
Once everything is aligned I would plug the top part of the vertical hole with a brass plug so that when grease is applied the grease would flow in the direction of the red arrows. As you can see to get grease to flow thru B2 I will need to drill some small escape holes through to the front of the roller.
Now the question.
Should I drill the vertical hole though the middle of one of the grooves (and have to deal with the vagaries of starting to drill a hole in a groove) as in OPTION A on the diagram
OR
Drill the hole starting on the outer shell of the roller as in OPTION B?
At full load speed the bearings are doing around 7000 rpm.
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