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Post by captbob on Feb 22, 2008 14:24:26 GMT -5
Edited to add: I think I have figured out the WHY, now I need the experts thoughts on a solution please. Post added... Okay, new question and hopefully not a new problem. On my salb saw when a cut is finished and I back the rock remaining in the vise out, there is grease on the lower leading corner of the rock. If it helps diagnose this, the rock shown is a couple/few inches out past the vise. But, it happens all the time no matter how much rock is sticking out. See picture...  Now these are going in a tumbler, so not a big deal as far as having a little grease on there. But, it could be a big deal if it means I have a problem that I don't know about. I can't find ANYWHERE that this grease could be coming from. It is on the saw blade at the end of each cut (shown below) but only in about a 2" band towards the center of the blade. There is no grease closer towards the center of the blade, like I think there would be were it coming from the hub - if that's even possible...  I'm thinking the grease on the blade is actually coming from the rock. So, how's it getting on the rock? Were I just cutting slabs and not tumbler fodder, I would have grease stained slabs. Any ideas? |
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Post by bobby1 on Feb 22, 2008 19:25:30 GMT -5
What you are interpreting as grease on the rock is really metal form the blade mixed with saw cutting oil. It comes from the rock being cut rubbing on the side of the blade and wearing it down. If you look at the smear on the side of the blade you can see the ridge of "grease".
It probably comes from the vise and blade being misaligned, causing the rock to rub on the blade.
Bob
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Post by stoner on Feb 22, 2008 20:51:25 GMT -5
Yep. And the way you check this, is to take a sharpie and clamp it in the vise so it's just touching the rim of the blade, then push the vise back towards the center of the blade and see if the line stays the same thickness or if it gets fatter(meaning the vise is getting closer to the blade as it travels toward the back of the saw) You can adjust the arbor so the vise rails are parallel to the blade.
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Post by bobby1 on Feb 23, 2008 10:55:11 GMT -5
From the red dimples on the picture of the blade it looks like this blade was sent back to the vendor to straighten it. When they straighten a blade they just whack it with a hammer in various selected locations, repaint it and let you have a go at using it some more.
Bob
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Post by captbob on Feb 23, 2008 12:38:13 GMT -5
Well, looks like I have a new problem with the Highland Park 24" saw... naturally Now I could use some suggestions on what to do about it. If the grease is actually metal shaved off the saw blade and the cause of this happening is due to misalignment of the vise (carriage) and the blade, I think I may know the reason. Please excuse me if I don't call each part by it's proper name. This is gonna be kinda long so that I make myself clear, but the pictures will probably explain it better. Okay, the drive screw (rod) that makes the vise carriage travel is broken at the back of the saw where it goes into the rear waybar. It is not completely broken, as there seems to be a solid bar INSIDE an outer sleeve. Why this bar isn't solid I don't understand, but oh well... Here are pictures of the back end of this screw bar. This shows maximum separation  Here is how I believe it should look  another shot showing the bar inside the sleeve  this is the front end of this screw rod (2 pictures showing the play in the rod)   here is a picture of the rod just to the rear of the threads where the "sleeve" begins  Again, I have no idea why this sleeve is on the back half of the bar, seems a solid bar would have been stronger. I also have a new blade that came with the saw if that matters. There still seems (to me) to be lots of life in the blade I'm using, but if it's bent and may have caused this problem I will replace it. I did the sharpie trick (3 different places) and the tip of the sharpie gets mashed in as I move the vise towards the center of the blade. So, any suggestions? I don't even want to know what a new bar costs! I figure I'll be taking the saw pretty much apart to fix this one *sigh*  |
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Post by bobby1 on Feb 23, 2008 14:16:46 GMT -5
If this is the back end of the drive screw shaft, this isn't unusual wear. Many saws have a bushing there that wears out. The shaft will also wear here but considerable wear at this point can be tolerated. The torque that is applied to this shaft as it drives the rock into the blade causes it to wobble.
The guide shafts on the carriage shouldn't have any wear, though. If you grab the carriage and try to make it move around, tilt, etc., any movement would not be good. The carriage should be firm but still move forward and back freely.
The problem with the "grease" is caused by the misalignment that was demonstrated by the felt tip pen. The carriage guide shafts are not adjustable, generally. You have to adjust the blade shaft-bearing assembly to correct the alignment.
I hope this description is understandable.
Bob
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Post by bobby1 on Feb 23, 2008 14:25:46 GMT -5
I forgot to add that the front of the drive screw shaft is the end that endures the most force, thus there is usually a thrust bearing or washer at this end of the shaft. On your saw this wear surface appears to be intact and normal. There will usually be some wear on the surfaces of the front and rear bushings, so slight movement front to back on the drive screw shaft isn't unusual or detrimental as long as the front bushing isn't badly worn.
Bob
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Post by captbob on Feb 23, 2008 22:25:25 GMT -5
Hi Bob, Thank you for getting back to me. Do you think that I should replace that rear bushing? Could the fact that it is a bit wallowed out have caused the problem that I have? And yes, the first 3 pictures are the back of the screw/drive shaft. As to adjusting the blade shaft-bearing assembly, I'm going to have to go out in the daylight to try to figure that out. I thought there were just two bearings holding the arbor, but I've never taken one apart. The previous owner recently replaced the arbor bearings. When you talk about carriage guide shafts, are you talking about the way bars that the carriage rides on? The carriage is tight, just out of line with the blade I guess. Looks like I'm going to get to take this baby apart after all. Good way to learn I reckon! If I replace that rear bushing, will I need to get that pressed out (and new one in)? Don't be surprised if I come back with another question or two  Thank you again for sharing your knowledge! Bob |
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Post by catmandewe on Feb 23, 2008 23:07:49 GMT -5
You should check the back half of the blade and make sure that it is an alignment problem and not a dished blade. Keep the felt pen going past the center of the blade and see if it gets wider or narrow on the back half. If it continues to get wider, then it is an alignment problem, but if it gets narrower again on the back half of the blade, then it is a dished blade. That blade has obviously been redone, so a slight dish would not be uncommon.
The bushings look good to me, as your carriage starts to move, it will naturally push away from the carriage, so the play is a non issue.
Tony
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Post by captbob on Feb 24, 2008 11:04:36 GMT -5
Okay, heading out for the shed to tinker with the saw, but I came up with a question (of course)
If the blade is dished, causing the rocks to rub up against it etc, can I just turn the blade around?
Seems it would be dished the other way then and not bind up against the rocks as they feed in. Just hate to retire a blade with that much life left in it.
Also, no one sems overly worried about the wallowed out rear bushing, so I assume that I should bother replacing it...?
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Post by bobby1 on Feb 24, 2008 14:17:24 GMT -5
I wouldn't worry much about the sloppy rear bushing. It doesn't impact the normal operation of the saw.
A dished blade is the most serious flaw in a blade. It is caused by the small point of the rock that occurs just as the blade breaks through the rock. If the saw stop switch isn't set exactly right, the rock continues to advance past the cut and the point rubs against the side of the blade. This permantly distorts the blade and causes the dishing. The further is advances toward the center of the blade the more dishing occurs. Because the blade has a certain level of tempering the dishing is generally permanent. (This process is taken advantage of in the process of making a metal bowl called metal spinning).
I frequently repair divots and tweaks in a blade caused by the rock slipping in the vise by placing it on my garage floor and whacking it with a dead blow hammer. This isn't effective with dishing because of the springiness created in the blade during the rubbing action. Reversing the blade just reverses the direction that the cut veers of a straight line during the cut. To check for any of these blade problems you can remove the blade from the saw and lay it on a flat surface. Any warps, dishing or divots can be readily seen. Sometimes a blade can be sent to a blade vendor for repair but they struggle with dishing because of the springiness of the blade. I'm not sure if they can repair it.
Bob
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Post by captbob on Feb 24, 2008 14:30:11 GMT -5
Hi Bob, Again, I thank you for taking the time to reply. I'm not cutting slabs where exact thickness is critical, just cutting thick slabs for tumbler rocks right now. Would reversing the blade take care of my "grease on the rocks" problem or just cause a new one?
As I wrote, I could swap out blades with my new one, but hate to waste this much blade. Will I do any harm by continuing to use this blade - and would you use it, retire it or reverse it?
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Post by bobby1 on Feb 24, 2008 16:10:33 GMT -5
If the blade alignment test with the felt tip pen indicates a blade alignment problem I would definitely correct it to get rid of the "grease" problem. Definitely correct this before putting a new, good blade on the saw.. If the blade has a slight dish I would reverse it and continue slabbing.
Bob
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Post by catmandewe on Feb 24, 2008 16:58:06 GMT -5
I would continue to use the blade you have on now. Especially since you are fairly new to cutting.
I hope I am wrong, but you will probably ding this blade before you wear it out.
If it is dished flip it around and keep using it. Only thing that can make it worse is if your rock comes loose.
Good luck with it, keep on slabbin...............Tony
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Post by rocklicker on Feb 24, 2008 17:17:44 GMT -5
I've reversed a blade on a 10 inch saw to fix the dishing and it did the trick. It takes a while for the blade to get back into alingment. At that point, you can reverse it back again or just leave it. Regarding the sleeve, I think it was desined like that intentionally. I have a big HP saw like that except it's a 16"er and I found that the threads ending naturally stops the rock from advancing and that sleeve is to keep it from going any farther. If your's is like mine, it has the screw drive AND a little pulley built in in case you want to use a weight instead. That sleeve is probably there to keep the rock from going any further if you use a weight to advance the rock.
Steve
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Post by captbob on Mar 1, 2008 15:54:29 GMT -5
Well I finally managed to get back out to the shed and take a look at the saw (read: it warmed up!) and... The blade is dished (so maybe not out of line). The sharpie test showed that the sharpie would flatten out towards the center and not touch the edges, once flattened out. I tried this several different places on the blade by rotating it and all showed the center dished out on the business side. So, I want to turn the blade around and see how it works that way. Which leads to what maybe my dumbest question yet! How do YOU take the blade off? I have a couple ideas, which I'm sure will work, but I wanted to know if there is a "right way" before I go and mess something else up.  Thank you for any replies which may save me from busting some knuckles! |
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Post by catmandewe on Mar 1, 2008 16:36:13 GMT -5
I put something in the pulley to keep it from turning, then use a wrench to take the nut off the end of the spindle. When you take the blade off, make sure you clean the shoulders of the washers and the mating surfaces of the blade as well as the shaft, as some gunk in there when you tighten it back up can cause a wobble in your blade. Then after your blade wobbles for a while, it starts slipping, then it heats up the blade and ruins the arbor hole, which makes the blade unusable.
(I know this because I have a 30" blade with an egg shaped hole in it)
Tony
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Post by captbob on Mar 1, 2008 19:38:52 GMT -5
Thanks Tony, I figured it was just standard taking a blade off procedure, just wanted to check.
Took it off and brought it inside to lay on the terrazzo (level and flat) floor and it's dished a bit. Couldn't tell so well from just the floor, but a metal carpenter's square showed it.
So, reversed the blade and... NO MORE "grease on the rocks" !!
Clyde is back up and running and all's right with the world.
Thanks to all for your input and helpful suggestions.
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Post by parfive on Mar 1, 2008 22:26:46 GMT -5
All may or may not be right with the world, Captbob. Seems like you've still got a dished blade, just running in the opposite direction.
Rich
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