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Post by engineerone on Jul 31, 2008 10:20:41 GMT
in the midst of re arranging the workshop, i remembered that i had to make a nick nack for a gift this weekend  so i used both the table saw and my 718 mitre saw. i change the blades on the table saw, but does one do so for wood as opposed to mdf on the mitre saw?? does it really matter? interesting aside, how do you stop the bottom of cuts on the smcs from burning??  paul  |
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Post by tusses on Jul 31, 2008 10:35:04 GMT
interesting aside, how do you stop the bottom of cuts on the smcs from burning?? paul wider kerf ? |
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Post by engineerone on Jul 31, 2008 10:44:58 GMT
i wondered whether it is because you should wait before the blade stops turning after the cut to move the wood, and of course almost always the wood is rubbing against the blade not sure the kerf makes any difference. mind you, thinking about it i need to de gunge the blade too. paul |
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Post by tusses on Jul 31, 2008 11:34:06 GMT
the kerf is wider than the blade, so the blade shouldn't touch the wood unless the blade has warped ?
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Post by andy on Jul 31, 2008 11:38:09 GMT
interesting aside, how do you stop the bottom of cuts on the smcs from burning?? paul I believe it is to do with tooth load so increase the feed rate or decrease the number of teeth and don't dwell |
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Post by sainty on Jul 31, 2008 12:07:05 GMT
mind you, thinking about it i need to de gunge the blade too. You've probably answered your own question. The blade could be blunt, or as Andy says feed rate/no of teeth could cause burning. I'd start by de gunging the blade. Rgds Stu |
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Post by ''The village idiot'' on Jul 31, 2008 15:16:46 GMT
mind you, thinking about it i need to de gunge the blade too. paul The answer my dear fellow is how well you maintain your tools. If you don’t bother to do regular maintenance on any of your tools, then you get Bodget and Scarper Incorporated results. |
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Post by sainty on Jul 31, 2008 17:20:53 GMT
The answer my dear fellow is how well you maintain your tools. If you don’t bother to do regular maintenance on any of your tools, then you get Bodget and Scarper Incorporated results.  easy there idiot, it's just a bit of burning!! rgds Stu |
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Post by gazza on Jul 31, 2008 17:31:21 GMT
mind you, thinking about it i need to de gunge the blade too. paul The answer my dear fellow is how well you maintain your tools. If you don’t bother to do regular maintenance on any of your tools, then you get Bodget and Scarper Incorporated results. Have to agree with that, 100% Look after your tools and they will look after you !! Cheers, Gazza. |
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Post by big-all on Jul 31, 2008 17:56:44 GMT
another cause could be the fence not parrallel to the blade causing the back edge off the blade to rub on the up stroke catching on the side off the teeth causing friction burns
often denoted by a 1/2mm deep channel in an arc on the wood where the teeth have worn a channel whilst the saw is slowing down or you pause the work for a couple off seconds
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Post by engineerone on Jul 31, 2008 18:11:45 GMT
of course maintenance is important but i get a clean cut for the top half of the the burn is always in the bottom corner, i guess mainly where the teeth actually are after you have run through the cut. i was always told to wait until the saw had stopped before moving the cut piece, and i hold the blade down at the end and bottom of its travel, but of course it will always slow down in part whilst being in contact with the wood. i can understand about feed rate, but why only at the bottom??? and none of this answers the other question, special blade for wood and one for mdf or no  paul |
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Post by ''The village idiot'' on Jul 31, 2008 20:02:27 GMT
and none of this answers the other question, special blade for wood and one for mdf or no paul Personally I use triple chip ground blades for all finishing cuts for cutting soft wood, hardwood, MDF or plywood. Mitre saw blades 4nr 200dia x 56 tooth count, triple chip ground. Table saw 5nr 250dia x 96 tooth count, triple chip ground. Slightest sign of burning the blade is replaced so I don’t get Bodget and Scarper Incorporated results. And when have 3 blades that need a little tender loving care off they go to the saw doctor. |
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Post by tusses on Jul 31, 2008 20:13:28 GMT
I never bother waiting for the blade to stop - nothing bad has ever happened ! Some do tho. How far up is the burn ? how about a sacrificial bed that raises the work piece ? until you find the correct correction  |
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Post by engineerone on Jul 31, 2008 20:55:51 GMT
i will clean up the blade, and then re test and report. i agree about a sacrificial bed on top of the base and that is above the root of the teeth, then i can check . as for not moving before the blade has stopped. i saw the film about the indian guy who chopped his arm off reaching behind a scms. so i always wait i work on the scms on the 100mm rule as with the table saw. cause one day it will catch, or i will tip the wood and it will slip paul |
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Post by Keith on Jul 31, 2008 21:08:54 GMT
If you lift the blade before it stops you will occasionally flick the offcut into the air, which can be fun, or very painful. I've found alternate bevel blades give a cleaner cut in MDF, when they are sharp! But triple chip blades are more durable, especially with MDF, and so if you use the saw a lot, overall/longterm you will get better results with a triple chip blade. Burnt cuts with MDF are usually caused by blunt blades, or cutting too slowly, which you often do when the blade is blunt Keith |
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Post by engineerone on Jul 31, 2008 22:07:20 GMT
erhh it was oak paul |
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Post by ''The village idiot'' on Jul 31, 2008 22:25:23 GMT
erhh it was oak paul Another post as clear as mud. |
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Post by paulchapman on Jul 31, 2008 22:30:03 GMT
If your blades are covered in gunge, that will cause them to over-heat as well, which won't help matters. Cheers Paul |
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Post by tusses on Jul 31, 2008 23:26:39 GMT
on the topic of gungy blades - what is a good solvent to clean them with.
And I dont mean expensive brand X - I mean houshold cleaner - white spirits paint thinners etc etc
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Post by big-all on Aug 1, 2008 0:13:29 GMT
sorry just realised your talking a slider l o l
the burning could be agrivated by your stance
or the gaurd mechanism being stiff causing an arc off centre towards the bottom
basicly burning can only happen at a "unusual "point if the blade move unaturaly in an arc where the side of the blade is cutting /rubbing after the teeth have done there work
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Post by Keith on Aug 1, 2008 7:23:05 GMT
If you lift the blade before it stops you will occasionally flick the offcut into the air, which can be fun, or very painful. I've found alternate bevel blades give a cleaner cut in oak, when they are sharp! But triple chip blades are more durable, especially with an abrasive wood like oak, and so if you use the saw a lot, overall/longterm you will get better results with a triple chip blade. Burnt cuts with oak are usually caused by blunt blades, or cutting too slowly, which you often do when the blade is blunt Keith ;D |
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Post by paulchapman on Aug 1, 2008 7:30:27 GMT
;D
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Post by big-all on Aug 1, 2008 11:57:28 GMT
another though
does the burning get progresivly lighter the farther up the wood you look
in other words darkest at the bottom through different lighter shades till the top!!!
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Post by Scrit on Aug 1, 2008 14:14:31 GMT
interesting aside, how do you stop the bottom of cuts on the smcs from burning?? :- As others say degunge the blade periodically, resharpen when needed and, for certain timbers, e.g. beech, sycamore and maple especially (although sometimes oak) don't use crappy old blade which have been sharpened a half a dozen times. Each time a blade is sharpened the clearance is reduced and with less clearance the blade is more likely to scorch on the topic of gungy blades - what is a good solvent to clean them with. And I dont mean expensive brand X - I mean houshold cleaner - white spirits paint thinners etc etc Try putting household cleaners onto the brazing that holds the teeth in place and you might find that it gets attacked by stuff in the cleaner. It's much better to stick to a modern aqueous solution, like that supplied by CMT (20/50 I think they call it). Unlike solvents (and traditionally the solvent was turps or turps substitute, being derived from the turpentine pine resin it readily dissolves pine resin) blade cleaner isn't inflamable, doesn't evaporate at a rate of knots and can be flushed with relatively environmental impact. 20/50 is actually cheaper tha using solvents as well as being better at removing carbonisation I never bother waiting for the blade to stop - nothing bad has ever happened ! If you lift the blade before it stops you will occasionally flick the offcut into the air, which can be fun, or very painful. It can also flick the offcut into the fence or your hand. I've had a few gouges out of my hands that way. i work on the scms on the 100mm rule as with the table saw. cause one day it will catch, or i will tip the wood and it will slip For your benefit, Paul, the advised hand-blade separation on table saws, spindle moulders, etc is 400MM, not 100mm Scrit |
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Post by engineerone on Aug 1, 2008 18:01:32 GMT
scrit only 66 per cent out then so what do you do if the bit of wood is only 200 mm long and for the record i did not suggest using turps or whatever. i use cmt which works very well. i do wonder though that others in the past have suggested using oven cleaner what is your view on that?? and what are your words of wisdom about the burning at the bottom. i keep thinking about the feed rate question, but since one is both going down and back, i do not really see how this changes much with an scms? paul |
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