Thread: Inserting a grease line into a set of bearings

Originally Posted by Michael G

Given that they are guide rollers, does the bolt need to be high tensile or will something like an 8.8 do?

Michael

(Psst - it was Phil not Bill)

Sorry I used the term "guide" rollers - they are not like a normal upright WW bandsaw guide rollers. The band is under quite a high pressure and makes a hard contact with with the rollers which push downwards on the blade to reduce band flutter and hold it flat in the cut. I guess the pressure on the rollers is not that high. I could try 8.8 but the thought of the blade coming of at speed will require the wearing of brown trousers. I have done it twice at low speed when I was trying to back out of a cut and that was bad enough - luckily no significant damage at all to the blade, a couple of teeth lost their edge but it was not noticeable in the subsequent cutting

I have not fitted the rollers so I have no pics of then but in this pic you can see the wooden blocks that are where the rollers would be located.
This is a somewhat puny log but you can see on the RHS the spray of water that hits the block (roller) on that side.
The photo doesn't really capture the amount of spray involved.
On bigger logs where the log is a lot closer to the LHS block/roller there is a lot of water being flung back onto that block/roller.
After a few cuts the blocks are covered in soggy crud and continue to be doused in water and sap.
.



Just to give you an idea of the size of the blade.
5335mm x 50 mm - the gizmo it's sitting on is the semi auto tooth setter - we also have the sharpener ( https://youtu.be/hyVHW2KhTWs)

I had a crack at the grease line through the bolt.

I decided to use an 8.8 bolt because I realised the tension on the band (which is along the band) is nowhere near the tension on the rollers (perpendicular to the band.

Parts

3 is a lantern ring spacer that separates the bearings creating a grease cavity.
A ~7mm wide by 2 mm deep groove has been turned on the inside of the lantern ring to enable grease to come through from the bolt hloe - through the lantern ring and into the cavity between the bearings.
1 is an external spacer that holds the roller away from the mill frame.
2 is another space that also protects the outside bearing from direct spray. The outer most seal of the outside bearing has 8 x 1.5 mm holes drilled in it for exiting of grease.

Here you can see the grease oozing out on the back side


There is a few tenths of a mm gap between the bolt spacer and roller on this side (see read arrow below) and I was hoping some grease would get from the cavity and past the internal bearing and sneak out through the gap so I would not have to drill escape holes in the front face of the roller. However, it appears the way out for the grease on the opposite side of the roller is too easy so I will have to drill some escape holes for the inner most roller.


The biggest problem was getting the grease gun to cooperate and output some grease!!!!

Nice work Bob, hopefully you'll have the problem licked.
Kryn

Originally Posted by KBs PensNmore

Nice work Bob, hopefully you'll have the problem licked.
Kryn

Thanks Kryn.
I just finished the other roller and that one has two exit holes drilled through the front of the roller so the grease can be flushed through the internal bearing.
I use a 2.5 mm bit and not having a cobalt bit it struggled to get through the roller material which is quite hard.
It's been an interesting learning exercise for me as I haven't dabbled with grease lines before but is shows what can be done with some useful input from fellow members.

Originally Posted by BobL

Thanks Kryn.
I just finished the other roller and that one has two exit holes drilled through the front of the roller so the grease can be flushed through the internal bearing.
I use a 2.5 mm bit and not having a cobalt bit it struggled to get through the roller material which is quite hard.
It's been an interesting learning exercise for me as I haven't dabbled with grease lines before but is shows what can be done with some useful input from fellow members.

You're right about the useful input, from the members. I am amazed at the amount of knowledge of some of the members here, some of it goes straight over my head, it's that technical, but very handy. I don't think I've seen a thread, that hasn't/can't be answered or replied to.
Kryn

Hi Bob,
Nice to see a bit of success.

Phil ( or Bill, I'm easy) lol

Originally Posted by Steamwhisperer

Hi Bob,
Nice to see a bit of success.

Phil ( or Bill, I'm easy) lol

Thanks Phi and for the idea as welll.

The boss is right pleased with the outcome (of course I took the credit ) but the proof will be in the test run next week

Originally Posted by Michael G

Given that they are guide rollers, does the bolt need to be high tensile or will something like an 8.8 do?

Michael

(Psst - it was Phil not Bill)

Posted by BobL

Sorry I used the term "guide" rollers - they are not like a normal upright WW bandsaw guide rollers. The band is under quite a high pressure and makes a hard contact with with the rollers which push downwards on the blade to reduce band flutter and hold it flat in the cut. I guess the pressure on the rollers is not that high. I could try 8.8 but the thought of the blade coming of at speed will require the wearing of brown trousers. I have done it twice at low speed when I was trying to back out of a cut and that was bad enough - luckily no significant damage at all to the blade, a couple of teeth lost their edge but it was not noticeable in the subsequent cutting

Metric Grade 8.8 is high tensile, and from memory is slightly higher in spec than Imperial Grade 5. I can't locate my references here and without resorting to Google, grade 5 has a tensile strength of around 120,000 lb psi, while grade 2 (metric equivalent grade 4.6), would be around 75,000 lb psi. A grade 8 imperial, roughly equivalent to metric 10.9 has a tensile strength of around 150,000lb psi IIRC, and I have the idea, but am far from being certain, that the metric standards are marginally higher than the imperial, but other than for the aerospace industry, in practice they are close enough to being equivalent.
So a metric grade 8.8 is not a soft bolt.
Rob.

Originally Posted by Ropetangler

Metric Grade 8.8 is high tensile, and from memory is slightly higher in spec than Imperial Grade 5. I can't locate my references here and without resorting to Google, grade 5 has a tensile strength of around 120,000 lb psi, while grade 2 (metric equivalent grade 4.6), would be around 75,000 lb psi. A grade 8 imperial, roughly equivalent to metric 10.9 has a tensile strength of around 150,000lb psi IIRC, and I have the idea, but am far from being certain, that the metric standards are marginally higher than the imperial, but other than for the aerospace industry, in practice they are close enough to being equivalent.
So a metric grade 8.8 is not a soft bolt.
Rob.

That's good to know.
The hole down the middle of the bolt is 45 mm long so I got most of the way there with a regular 1/8 HSS bit and just the last 5 mm or so I did with a 1/8" long bit. It seemed to chip out a bit more than mild steel but otherwise it did not seem that hard.

That sounds pretty right Bob, ordinary HSS would have no trouble handling it or even grade 8 (M10.9) for that matter. Easier to get a good finish as the chips are less stringy than mild steel, you might sometime have to reduce speed if you are already at full bore for mild steel, but you already knew that.

Originally Posted by BobL

Thanks Phi and for the idea as welll.

The boss is right pleased with the outcome (of course I took the credit ) but the proof will be in the test run next week

My fingers are crossed for you as well Bob.

Phil