Bendy Scrollsaw Blades

[Gill]

I've been participating in a discussion about a propensity for some scrollsaw blades to bend backwards in the top retaining clamp. It's certainly a problem I've encountered and when I raised it with Hegner UK I received this email:

• Dear Gill
  
  The bending of the blade ends is caused by not placing them exactly in the centre of the "V" of the blade clamp. I also have the problem a lot but have come to the conclusion that most of the time speed is preferable over accuracy in this matter as it never seems to effect the accuracy of my work.
  
  Best regards,
  Roger Buse

What are other peoples experiences and can anyone suggest how to avoid this problem? Incidentally, I've always tried to align my blades centrally but to no avail - the problem persists.

Gill

 

[dedee]

Gill,
can't say that I have ever noticed mine doing this.

Do you think that it is causing an accuracy problem in your work?

Andy

 

[Gill]

Hi Andy

I understand it can cause very minor inaccuracies when working on thick pieces of timber, but I haven't noticed any on the work I do.

The real problem comes when you try to insert a blade into a fine drill hole for fretwork or intarsia - bent blades don't fit into small holes! Added to which, the life of the blade is shortened by the bend weakening the blade and eventually breaking it. I prefer to throw out my blades because they are blunt than because they are broken.

Gill

 

[Chris Knight]

Gill,

I have a crummy imported scroll saw that I hardly ever use so I can claim no relevant expertise but your question intrigues me.

I guess the bend you refer to is fore and aft - in line with the cutting direction? Assuming this to be so, then surely the only way your blades can bend is if you push back too hard on the workpiece whilst cutting? In other words the free part of the blade is bent backwards and the fixed part in the clamp is held rigid?

In this case, the remedy would seem obvious but I guess you know this so I should like to understand the nature of the problem in a bit more detail.

Sorry I have nothing to offer in the way of useful advice!

 

[Gill]

Hi Chris

Considering you're not a scroller, it's very kind of you to take an interest in this.

The bend is rearwards, always towards the rear of the saw and in line with the cut. I'm sure it's not down to how I feed the workpiece because I'm not the only one who experiences this problem. If the resident expert at Hegner UK also suffers with it, then it's not likely to be attributable to that aspect of user error.

The clamps that hold the blades are held in rockers on the arms. The bottom clamp swings free in its rocker but the top clamp is fixed on the arm by a screw. I'm beginning to suspect that this may be where the problem lies. When I first purchased my saw (many years ago) I was told by the Hegner rep that the screw should be tightened to ensure alignment when changing blades and that there was no need to release it again when sawing. Perhaps I should be releasing the screw to saw and only tighten it when changing the blades. Next time I'm using the machine, I'll try this and see what happens.

Gill

 

[Chris Knight]

Gill,

I have looked at a load of Hegner images on Google but can't see the top fixing very well in any of them - there does appear to be a fair variety of fixings - some obviously quick release, others not so.

From your description, it does sound as though the bottom clamp rotates during the stroke, enough at least so as not to kink the blade but rather to permit a smooth curve from clamp into the blade as the blade is inevitably bowed by the sawing process. In the case of the top clamp this would appear not to be the case, so your suggestion to release the screw sounds logical - so long as it doesn't allow the clamp to shift back and forth but only to rotate (oscillate) about a centre.

 

[Argee]

Gill,

I've had my Hegner since October 2004, so my manual is probably as up-to-date as they come. It says that there should be a small clearance between the top rocker and the screw if that helps. If you'd like a copy, send me a PM.

Ray.

 

[Gill]

I tried using the Hegner today with the top clamp riding freely in its seat. Alarmingly, it bent forwards quite dramatically; however, there was no further bending of the blade. The only dilemna I now have is what I do when the clamp is in this position and I find I need to release the blade for piercing work. I certainly couldn't refit the blade at such an angle.

I tried several practice cuts today and each time I replaced the blade I aligned it properly in accordance with the instructions. It seemed to work okay, but time will tell - I haven't employed the saw yet on a major project using this technique.

Gill