Band saw guides - are "Cool Blocks" good?

richard newman · Feb 6, 2014

Building a resaw power feed gizmo that will include a bottom guide, and I'm wondering if I should use Cool Blocks. Are they as good as advertised?

I prefer guide blocks to ball bearings, chips find there way in there and jam the blade or throw the bearings out of adjustment, plus they are noisy. My Tannewitz has hardened blocks, they work great, wondering if Cool Blocks are an improvement. I want to set them up with minimum clearance.

wbtracey · Feb 6, 2014

I think the short answer is no, not as good as advertized. I haven't got any direct experience with Cool Blocks, but they seem to have a pretty negative reputation. Search the term "fool blocks" over on owwm and you will find all kinds of less than favorable impressions of them. At RIT the students seem to find creative ways to trash guide blocks on our saws, so I've had the pleasure of fooling around with the various options out there. The ones I have found hold up best are the brazed carbide ones sold by Carter:

CP10-10C Carboloy Blocks | Carter Products

Those blocks are stupidly expensive though at $117 per pair. I've had a set on our 36" Northfield for a few years. For what you are up to I wonder if you could just braze your own, or maybe there's some creative way to set up brazed carbide lathe tooling as guide blocks.

Will

PeteM · Feb 6, 2014

I can give a somewhat more favorable response.

First thing is that they are basically a graphite impregnated phenolic laminate. There are other sources for the material than the official "Cool Blocks." Even the Cool Block branded ones are likely under $25 when bought as a direct replacement for the hardened steel blocks your saw probably already has. What you don't want is "clones" that are just pieces of plastic without the phenolic/laminations/graphite lube. Those would, indeed, be "fool blocks."

Second thing is that these are best for very narrow blades (think 1/8, 3/16, maybe 1/4"), which must essentially be buried in the blocks for proper guidance. Yes, they'll wear. But the graphite lubed material is much easier on the blade than inadvertently shoving the teeth against hardened steel (etc.) blocks.

For wider blades and cutting metal rather than cutting sharp radii in wood, the original hardened metal, ceramic, carbide, or roller guides (more common in wood) are the way to go. Cool blocks will work, but will wear and need attention more frequently.

One other point is that some folks don't pay all that much attention to how their blades track and how the guides are set. It takes just minutes to touch up the edges of either the phenolic or hardened steel blocks, but from what I've seen in various shops (and bought as used bandsaws) -- the last time those minutes of attention were taken may have been years ago. It's very common to see solid guides that are bell mouthed toward the teeth and not even particularly well placed at the back.

crashtestdummy · Feb 6, 2014

I have a 14" Delta bandsaw that I used Cool Blocks on. They were OK, but I now use ceramic blocks and I'm able to keep the blade held tighter so there is less play when cutting radii.

MCritchley · Feb 6, 2014

I bought the ceramic blocks from Louis Iturra for my wood / metal delta 14". He stated that the cool blocks can get chewed up if anything but wood goes thru the guide.

They work good, i dont do much conture work. I mainly do resawing.

PeteM · Feb 6, 2014

As just one other point of reference, my Laguna bandsaw with an 18" depth of cut came with ceramic guides. I liked them for resaw and gentle curves. I preferred the ball bearing guides I'd had earlier on a 12" depth of cut Rockwell saw for blades 1/4" and less wide, especially with tight contours. The blade, at least for me, tended to occasionally pull out of the Laguna guides and even spark as it attempted to find its way back in. Even when a narrow blade stayed within the guides, the control seemed a bit worse than properly adjusted ball bearing guides.

Ceramic, on the other hand, runs for a long time in wider blades with little or no attention.

richard newman · Feb 6, 2014

Hmm, not so cool after all. I was thinking maybe the blade would run cooler with tightly set guides, which actually has not been a problem, so I guess I'll just go with some hard steel. Not sure I want to bother with carbide, the machines here don't run night and day, easy enuf to dress the steel on the surface grinder. When I got my surface grinder the first thing I did was reface a box full of worn blocks that came with my Tanny, easily a lifetime supply!

Would hss or tantung hold up better than O1 or 4140? Have lots of cutoff blades I can scavenge.

comboprof · Feb 13, 2014

richard newman said:
Building a resaw power feed gizmo that will include a bottom guide, and I'm wondering if I should use Cool Blocks. Are they as good as advertised?

I prefer guide blocks to ball bearings, chips find there way in there and jam the blade or throw the bearings out of adjustment, plus they are noisy. My Tannewitz has hardened blocks, they work great, wondering if Cool Blocks are an improvement. I want to set them up with minimum clearance.

I recently bought an old 20" bandsaw and could not find "cool blocks" to fit it. So I made my own. I followed the following recipe which I found online. Choose the hardest wood you can find. I happened to choose Iron wood, but any will do, even hard maple. There are some pretty hard exotic woods. Bocote is a popular choice. You can get blanks for turing pens at say woodcraft.

Cut to fit the required blocks. Note you can make them extra long too.
Soak in mineral oil covering entirely the blocks 48 hours.
While still covered in mineral oil microwave 30 to 45 seconds.
Remove from oil and dry off residue oil.
Install blocks and/or store spares in plastic baggies.

Mine came out great and work great. You can push them up to the blades and you can easily cut or sand new faces as they wear. You can use other oils. I have read that wd-40 is often used. I use mineral oil in finishing and did not want to risk using an oil that would stain my projects. I do not know what is optimal.

stephen thomas · Feb 13, 2014

Choose the hardest wood you can find. I happened to choose Iron wood, but any will do, even hard maple. There are some pretty hard exotic woods. Bocote is a popular choice. You can get blanks for turing pens at say woodcraft.

Hee, hee.

I take it you have not seen/heard of Richard's exotic stash?

Interesting idea, though. I'd start with cocobola as a relatively cheap, very hard, already oily wood with lots of scrap around here. If Lignum vitae is not on the shelf somewhere.

I use mineral oil in finishing

Interesting. Can you say more?
Is this for cutting boards, or other wooden objects as well?

smt

comboprof · Feb 13, 2014

stephen thomas said:
Hee, hee.

I take it you have not seen/heard of Richard's exotic stash?

Interesting idea, though. I'd start with cocobola as a relatively cheap, very hard, already oily wood with lots of scrap around here. If Lignum vitae is not on the shelf somewhere.

Interesting. Can you say more?
Is this for cutting boards, or other wooden objects as well?

smt

I did read where one fellow used cherry, bit yes Lignum vitae would be good. Matthias Wandel over at woodgears.ca writes:
"If you don't have any exotic hardwood handy, use the hardest hardwood you have, and soak some oil into it." So I think one of the
oily exotics may not need to have extra oil soaked in.

I do use the mineral oil on cutting/cheese boards so I thought it would be a good choice for the bandsaw blade guide application.

richard newman · Feb 13, 2014

Hmmm… Lignum sounds ideal, was/is used for huge turbine and propeller shafts, lots of little blocks in a stuffing box. Supposedly the seawater makes the lignum real slick.

Lignum-Vitae-Bearings

I have some, might be worth a try. I've also got a micronizer that puts out a very fine spritz of cutting oil on the blade, should keep the Lignum well lubed. Or maybe I could just use water,price is right, so long as it doesn't rust up my saw.

Fabitfast · Feb 13, 2014

I always prefer ceramic blocks.

stephen thomas · Feb 13, 2014

Cherry does not sound like the ideal starter wood - it is so susceptible to burning from friction contact. But if it works, hey!

I was up in the loft for other reasons and found a pile of hop-hornbeam (USA "Ironwood") so maybe that would be worth an experiment with oil, sometime in the future.... where projects don't even have a number yet!

On that note, dogwood was traditionally used for quality brake shoes (& later clutches) back when horsepower was provided by, well, oxen and horses & occasionally steam. Because it did not burn easily from friction. Hard as blazes, too. Though i no longer know for sure where my stash of that went.

Osage is very hard & sort of oily, but smells like tomcat pee. Lilac might have potential. Yew is hard as rocks (makes chainsaw throw sparks!), but maybe the resins would be counter productive.

smt

comboprof · Feb 13, 2014

Here is a picture of the blocks I made from Ironwood:

The top two are 5/8 by 5/8 by 3/2. So 1/2 inch longer than the original. I might make them 2 inches next time around. First I will see how long they last. I'm waiting for my 3/4 inch wood slicer re-saw blade to arrive from highland woodworking. Then I can truly put these guides to the test.

comboprof · Feb 20, 2014

stephen thomas said:
Cherry does not sound like the ideal starter wood - it is so susceptible to burning from friction contact. But if it works, hey!

I was up in the loft for other reasons and found a pile of hop-hornbeam (USA "Ironwood") so maybe that would be worth an experiment with oil, sometime in the future.... where projects don't even have a number yet!

On that note, dogwood was traditionally used for quality brake shoes (& later clutches) back when horsepower was provided by, well, oxen and horses & occasionally steam. Because it did not burn easily from friction. Hard as blazes, too. Though i no longer know for sure where my stash of that went.

Osage is very hard & sort of oily, but smells like tomcat pee. Lilac might have potential. Yew is hard as rocks (makes chainsaw throw sparks!), but maybe the resins would be counter productive.

smt

Came across the articles I had read on this again today. So I thought I would add the references.

Here is Howard Ruttan's article on how he used straight grained cherry and WD-40 for making guide blocks:
Hardwood Bandsaw Guide Blocks.

Here is the article by George Oxford from which I took the recipe posted above: Make your own cool blocks.

As far as I know I am the first to use "ironwood". If I had some lignum vitae, I would have used that.

richard newman · Feb 27, 2014

Lignum Disappoints

Ok, I made some lower guide blocks of Lignum, thought they'd be the nuts. The wood is so oily it feels like really hard soap or wax. The lignum blox are 1" high, 1/2" deep, adjustable with slotted holes for the cap screws. The blade is 1/2" wide and I adjusted the blox as snugly as possible without creating drag on the blade. Used the machines upper and lower guides (ball bearing rollers) also.

I re-sawed 250-300 pcs of maple, walnut, cherry and mahogany, 4' x 3". Maybe 3-4 hrs run time in all. Seemed to work really well, got good accuracy and consistency, but when I took the set-up down I noticed quite a bit of wear on the blox, as you can see in the pix.

I'm thinking next to try hardened or high speed steel next, or maybe carbide.

mike 44 · Feb 27, 2014

stephen thomas said:
Cherry does not sound like the ideal starter wood - it is so susceptible to burning from friction contact. But if it works, hey!

I was up in the loft for other reasons and found a pile of hop-hornbeam (USA "Ironwood") so maybe that would be worth an experiment with oil, sometime in the future.... where projects don't even have a number yet!

On that note, dogwood was traditionally used for quality brake shoes (& later clutches) back when horsepower was provided by, well, oxen and horses & occasionally steam. Because it did not burn easily from friction. Hard as blazes, too. Though i no longer know for sure where my stash of that went.

Osage is very hard & sort of oily, but smells like tomcat pee. Lilac might have potential. Yew is hard as rocks (makes chainsaw throw sparks!), but maybe the resins would be counter productive.

smt

I use cherry for guides because I have a lot of it.My saw came with cool blocks.They work fine and I use the cool blocks most of the time.When I use a narrow blade I switch to the cherry guides.This way the guides can touch the teeth without damage to the guide blocks or the blade teeth.I never bothered oiling mine,sounds like a good idea though.

mike

PeteM · Feb 27, 2014

It looks to me like your guides don't have a support (ceramic, roller, etc.) to take the pressure of cutting? There's likely something, but perhaps inches above and below the area shown in your first photo? If so -- this would allow the blade to deflect deeper into the side guides -- giving you the bell-mouthed appearance they've taken.

Try the same with hardened steel side guides -- with inadequate thrust support -- and you might just dull the outside set of the blades.

richard newman · Feb 27, 2014

I used the machine's regular guides just above the cut, and in the usual place below, which backed up the blade as they usually do. The bottom thrust bearing is 4" below the table, so I suppose the blade might flex a bit, but hard to imagine it flexing that much.

These guides were just prototypes, when I get something I like I'll add a thrust bearing behind the blade just to be sure. Don't want to hit the teeth, especially if I use a carbide blade.

catalytic · Mar 17, 2014

I agree with the others that cool blocks are junk. The best guide blocks are ones that give good support to the blade and don't wear out fast (they never seem to wear squarely, so a worn guide tends to only touch the blade in a narrow section). Some good guides (Davis and Wells for one) used carburized steel guide blocks. I have also seen some people braze carbide faces onto steel guide blocks for super overkill.

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