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General Category => General Scroll Saw Talk => Topic started by: saggioculo on May 19, 2013, 10:04:56 am
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So, you can see in the picture that I keep bending my blades. It seems like no matter how I try to tighten the blade in the saw...the blade seems to twist with the screw and I end up bending the blade. It doesn't happen with my other blades, just the spirals. GRRRR!!! What am I doing wrong?
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Looks to me like you are over tightening the blade. check the adjustment on the set screws, and clean the ends of the set screws and tightening screws
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From the picture it looks like you have a kink on both ends, one more severe than the other and I am guessing the more severe one is the bottom - meaning I have been there and done that. First check your set screws as already suggested. Then you need to experiment some to find the sweet spot and just the right feel and position for your thumb screw so it is not hard to tightened, it is really a matter of feel. I have found generally that the top of the blade should be toward the lower part of the slot (EX 21) for the top set screw/thumb screw. I always want the top to not kink because I feed the blade through the work from the bottom up and a kink in the top will not let me do so. If you feed from the top down you will want to make sure the bottom does not kink. I frequently get it right and do not have a kink on either end but I can live with a kink at the bottom. I may still be doing it wrong but I think it may be somewhat unique to spirals and I almost exclusive use FD 2/0 spirals. Flat end blades do not present the problem.
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Looks to me like you are over tightening the blade. check the adjustment on the set screws, and clean the ends of the set screws and tightening screws
I didn't know it was possible to over tightening. I thought...the tighter the better. What are the "set screws"...I'm assuming I know what the "tightening screws" are but those are the only screws I see and use when installing/removing the blade.
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Set screws may depend on your unit. On the DW788 and EX21 both the upper and lower blade clamps/chucks the set screws are exactly opposite (on the left hand side) of the thumb screws (on the right hand side). If the set screw has loosened some you will be tightening the blade into the set screw hole and getting the kink in the blade. This will be a bigger problem on a spiral blade which is spiral from end to end than with any flat end blade but you should also notice problems with flat end blades. I have a flat piece of metal that slips into the blade slot and to check the position of the set screw I put the metal piece in the blade slot and then tighten the thumb screw to hold the metal piece in place. I then use the allen wrench required to tighten the set screw and tighten the set screw against the metal which the thumb screw is holding in place - this makes the thumb screw flush with the inside of the blade chuck. I also use blue loc tite to try to prevent the set screw from loosening.
Even when the thumb screw is set correctly, it will not solve all of your problems with spiral blades that are spiral from end to end. Look closely at the end of your spiral blades to see the twist that is in the blade. When inserting the blade into the blade chuck I cannot see how the spiral engages with the set screw and thumb screw as tightened but I am guessing part of the spiral which is flat needs to engage in order to get the tightening without the kinking and that this is why even if I get one end okay, the other end may or may not tighten without kinking. You might also, as you are trying to find the right spot slightly twist the blade between your thumb and foregoing as you are holding it in place to tighten the thumb screw - raising the blade up and down a bit and possibly slightly twisting should help you find that spot where you can at least tighten the end you need straight without kinking it. Also, you can over tighten. You may have to use some force to tighten on the one end some of the time to get it to hold but if you are using flat ends only you should never have to use a great deal of force. I have had to replace blade chucks on both my DW788 and EX21 as a result of over tightening as I also had originally thought the tighter the better. I found out that continually tightening with as much force as possible results in thread stripping and chuck replacement.
I hope some others will weigh in with their experience as I am only sharing my experience and would love to learn more on the subject in case I am still doing things wrong.
Good luck.
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I'm using a 10 year old Ryobi with a whole lotta hours on it. I was saving up to get a new saw...maybe an excalibur or hegner...then I was robbed. Police caught the guy (who is still awaiting trial), but I doubt I'll ever see a penny of that money ($800 I had saved up).
Anyway, I looked but still can't find the "set screws"...is it possible that my saw doesn't have them?
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I have this problem by just even the screws just touching the blade end it will start or bend and follow the screw when trying to tighten down, I gave up on them.
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I suppose it is possible the Ryobi does not have a set screw opposite the thumb screw, I am just not familar at all with the Ryobi and doubt there would be a good on line picture of the blade clamping system for a ten year old. I really think if you are not having problems with flat end blades that it is just a matter of sliding the blade up and down a bit and/or twisting it a bit while to try to find the place which permits tightening without kinking. You should not have to clamp hard while looking for the spot and once you have discovered the technique you will be able to do it rather quickly - just do not count on being able to get both ends tightened without a kink in at least one so find the end you do not want kinked and tighten it first with this procedure.
Good luck.
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With blades that spiral all the way to the end, you will always have the condition that the thumb screw hits the blade on one side but the blade is not yet contacting the clamp on the other side. Then as you tighten the thumb screw, the blade bends until it contacts the opposite side. I can feel this on my saw - there is resistance on the thumbscrew for a turn or so before it gets tight. I don't get that resistance on flat blades - it just lands and gets tight.
The thumb screw on the EX-21 has a piece on it that floats like the end of a C clamp screw so turning the thumb screw does not put a shearing force on the blade. You might check yours to see if that thumb screw end is free to rotate.
You can flatten the ends of the spiral by laying it on a hard surface (an anvil or a piece of flat steel) and tapping it with a hammer. Try to flatten both ends so they are parallel. Then they should tighten like a regular flat end.
If the setscrew was out of position then you would be bending flat end blades as well. If those are not bending then the setscrew is either good or does not exist on that clamp.
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With blades that spiral all the way to the end, you will always have the condition that the thumb screw hits the blade on one side but the blade is not yet contacting the clamp on the other side. Then as you tighten the thumb screw, the blade bends until it contacts the opposite side. I can feel this on my saw - there is resistance on the thumbscrew for a turn or so before it gets tight. I don't get that resistance on flat blades - it just lands and gets tight.
The thumb screw on the EX-21 has a piece on it that floats like the end of a C clamp screw so turning the thumb screw does not put a shearing force on the blade. You might check yours to see if that thumb screw end is free to rotate.
You can flatten the ends of the spiral by laying it on a hard surface (an anvil or a piece of flat steel) and tapping it with a hammer. Try to flatten both ends so they are parallel. Then they should tighten like a regular flat end.
If the setscrew was out of position then you would be bending flat end blades as well. If those are not bending then the setscrew is either good or does not exist on that clamp.
This is type of spirals I have all the way to the end, I may need to flatten the ends and try again.
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Don't do the spirals, but do know that FD Mike has FLAT END SPIRALS. Danny :+}
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This is slightly off-topic so I hope you will forgive me.
Doug (PigsFly)! I have been having a lot of (flat) blade slippage of late and think it is because my set screw isn't aligned correctly. I can't see well in there and actually planned to ask a question tonight to ask for a good method for getting things right. What you posted makes it so obvious I want to slap myself in the forehead! Anything that makes me want to do that is a simple, (now) obvious solution to a problem that has been bugging me.
I just wanted to interrupt this thread long enough to say thanks for that idea.
And now back to our regularly scheduled programming. :)
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Becky
If you are having slipppage you probably also want to follow the suggestion of cleaning the ends of the set screw and thumb screw if you have not already done so. Also, having said how I set the thumb screw, I should note the EX21 manual shows the set screw protruding out slightly into the blade slot. If you decide to follow the manual you might want to do my procedure and then give the set screw another 1/8 to 1/4 turn. I just have it flush without the extra turn.
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One other thing about the EX-21 setscrews (and probably most other saws) - there is nothing holding that screw in place as it comes from the vendor - it is just a screw in a threaded hole, adjusted to center the blade in the clamp. Seyco has recommended to me to remove the setscrew (NOT the thumbscrew!), put of a drop of BLUE Loctite on the setscrews, then adjust the setscrew to center the blade (both top and bottom clamps). The BLUE type Loctite will hold the setscrew in place, but can also be overcome by hand tools without adding heat.
Without that Loctite, the setscrew will continue to back out as used and will have to adjusted regularly.
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Thanks, guys. I e-mailed a friend of mine who works with a lot of metal and he brought me a piece of stainless steel for trying your method. I found that when I snugged up the stainless against the side of the slot using the thumbscrew and then snugged up the set screw, I was unable to loosen the thumb screw. Too tight? I loosened the set screw by a quarter turn and was then able to loosen the thumb screw. Then I put back the set screw's quarter turn.
I am not going to really be able to tell how well this works until the weekend. I am in the middle a a lot of deadlines at work and am too tired when I get home to do any serious scrolling. I'll be fresh come the weekend and will be back at the fretwork on a couple of projects. If the blade holds up well with the adjustment, I will use some of that Loctite stuff. I just want to make sure the adjustment is good before going there. I may find that I need to make it protrude a little for best results. And I might also pull out both screws and sand them up a little. I haven't done that in a while though I do always sand up the blade ends before inserting them. I should be awake enough to do that tomorrow night.
At least I think I am now on track to get this sorted out. Maybe I will be able to spend more time cutting this weekend than I spend cussing at my saw!
Sorry again for the thread hijack but I do appreciate the tips.
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Becky
Be sure to let us know what worked.
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I worked with the saw today after adjusting it. I never did clean up the screws (what can I say? It has been the month from hell.)
I had much better luck after the adjustment but it still let go a few times. A little cussing was in order but not nearly as much as last weekend. :) The most annoying thing is that now my thumb screw gets snug when it is horizontal instead of when it is vertical. It is surprising how much more difficult that is. Do you suppose taking it completely out and giving it a quarter turn before reinserting it would fix that? I don't really know how threads work, so that is either a simple or really stupid idea, lol.
I might try that 1/8 or 1/4 quarter extra turn tomorrow. If that doesn't fully fix it, I guess I will break out the sandpaper. With so little time to actually scroll, I hate to waste it experimenting if things are going fairly well.
This is probably not a very satisfactory report. I have hopes of being on vacation in a week or so. I should have more time to play around with it then if all goes well.
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If you turn the setscrew in or out another 1/4 turn then the thumbscrew will hit it 1/4 turn earlier and be vertical.
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That worked perfectly! A quarter turn pushed the set screw out just a little and got me back to vertical with the thumb screw. The slippage is largely resolved since I did that. I still might take them out and sand them one of these days and perhaps tinker just a little more but all is right with my world again.
Poor saw got so much unearned cussing from me these past few weeks it went from yellow to blue! ;)
Thanks again for the initial tip and for your continued refinements. Getting the set screw adjustment figured out is about as exciting as learning to put wax on the saw table. LOL, anybody who doesn't scroll would read that and wonder about my mental health. Lest I leave that hanging (it IS way too easy after all), I'll add that I know my fellow scrollers understand. ;D
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If the knobs are hard to turn, Steve has a patten for wood "overlays" to make tightening easier. http://stevedgo.ipower.com/cat/?page_id=170 (http://stevedgo.ipower.com/cat/?page_id=170) The pattern mentions the EX21 and DW788 but it could be used for any saw. It would also mean you wouldn't have to adjust the set screw so the knob was vertical.
Do check the underside of the table to make sure the wood knob doesn't hit the table.
Jim
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Thanks, Jim. It isn't hard to turn the screw normally (when it is getting snug close to vertical). I just struggled with it more when the snug point had it horizontal. It just felt awkward. Since I was thinking about making the set screw protrude a little ways into the gap anyway, Ray's solution fit the bill perfectly!
I was thinking about making one of Steve's gizmos there for a while though.
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Hey Becky...I use 2/0 & 3/0 spirals constantly and I have learned that just wiping the ends of the blades with good ol' drugstore 91% ALCOHOL solves most of my problems with slipping.
I made one of the blade holder attachments by Steve for my upper blade holder screw and it works great. BUT, I tried it on the bottom and it hits the underside of the saw table.
Doing the set screw adjustment is your best treatment for the lower blade holder screw travel. I finally got my setscrew where it works well and then took it out, put on some BLUE Loctite and have been cutting along merrily ever since....
~~~GB~~~