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Straight lines on a scroll saw

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StevieB

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Having finally got my hands on a scroll saw (Rexon SS16SA for £79.99 from B&Q, apparently they are a discontinued line, hence the price) I was happily having a play at the weekend and quite like it.

I have ordered a pattern to have a go at but it has a number of straight lines in it which from my play at the weekend I think are going to cause me problems. Does everyone have problems getting straight lines to look straight, or do you cut them and sand them straight afterwards? I did think about clamping a batten to the table and running the piece along that, but since the table is not square edged getting the batten parallel to the blade would be a problem I think. I also considered a point fence level with the blade but again Im not sure this would be any better than freehand cutting. If its just a question of time and practice thats fine, I just need to warn SWMBO not to expect too much from the first attempts to make it out of the workshop!

Any hints or tips greatly appreciated. I have a selection of blades from axminster and am cutting 6mm birch ply.

Cheers,

Steve.
 

Gill

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Hi Steve

Congratulations on your new saw and welcome to the club :) ! What are the the technical details of your new baby (throat, stroke speed, stroke length, max depth of cut, table tilt) ? I can get very curious about these sorts of things.

Okay, cutting straight lines. Most scrollsawyers learn to do this freehand and it takes practice. Fences can be used on a scrollsaw but they are unreliable because of the nature of the blades that are used. If you think about it, saw blades that general woodworkers use to cut timber straight tend to be rather deep (eg table saw blades, resaw blades). As the blade becomes progressively less deep, there is a greater tendency for the cut to become less reliably straight (eg bandsaw blades). Scrollsaw blades represent the extreme position. As I understand it, this is because the set of the teeth on a scrollsaw blade is proportionally much wider to the depth of the blade. Added to which, a slight unevenness in the set of an individual blade can make a big difference to how the blade tracks.

It is possible to construct a fence that will compensate for a general bias on a brand of blade, but there will still be some error. A simple finger fence such as you might use on a bandsaw would probably be more useful, especially if the straight cuts are going to be rather long.

I'm currently trying to accumulate a range of different types of scrollsaw blades so that I can test them for this error and decide which I prefer. The blades that come with your saw are unlikely to be the best available so it might be worth looking for some that are recommended by other scrollsawyers. I'm currently awaiting the delivery of some Flying Dutchman blades from the US that have a very good reputation.

If you're going to cutting plywood, tear-out on the underside of the timber will probably be a problem with a standard blade. You can reduce this by using a reverse-tooth blade which cuts on the upstroke as well as the downstroke. I've just found this link: http://www.shesto.co.uk/acatalog/Shesto ... ES_41.html and think I might be ordering some of these blades myself. It would be worth checking your Axminster blades to see if there is a reverse-tooth blade in the selection you have.

Hope this helps.

Gill
 

StevieB

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Thanks Gill, technical specs are as follows:

16" (406mm) throat, 200w motor, 45 degree tilt left, 50mm max cut, 19mm stroke, table size of 415mm x 250mm in an oval/teardrop shape and blade speeds of 900 or 1400 strokes per minute.

I read with interest the thread on blades a while ago, look forward to your conclusions. One other question, what material feed rate would you recommend for a beginner? Should I go slow and try to follow a line exactly or go slightly faster but concentrate on getting a smooth flowing line?

Looking forward to the weekend now! This is the plan I have ordered:

http://www.hobbies-dereham.co.uk/ho...PG2CD8HKDPHMFGX7942AS7RP6&dept_id=&pf_id=0315

But I am rapidly coming to the conclusion something a bit simpler may have been a better idea :roll:

Steve.
 

Gill

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Hi Steve

It looks like you've got a lovely machine there :).

I've just noticed an embarrassingly loose turn of phrase in my previous post when I mentioned that blades 'track'. Of course, scrollsaw blades don't 'track' in the way that a bandsaw does - what I was really describing was the blade bias. I hope I haven't caused any confusion :oops: .

That grandfather clock pattern looks very attractive and you may be able to produce it successfully at a first attempt. I've made one or two projects from Hobbies' plans and they're usually very good, although I've always had to make adjustments to compensate for using metric measurements and timber cut to metric thicknesses. The standard advice for anyone new to scrollsawing is to pick up a book with a range of patterns so that you can start with something fairly simple and progress to the more complicated as you get to know your saw better and your skills develop. Although they're American, Patrick Spielman has published several very good pattern books that you might consider. To my mind, it's far better to learn to cut accurately from the outset using simple patterns rather than trying to cut quickly. If your basic technique is sound, your speed will pick up as you gain more experience.

The material feed rate depends on the type of material that you're using, grain direction (if appropriate), thickness of the material, the type of blade being used and stroke speed. You'll have to work it out for yourself! Generally speaking, you should try to feed the material in at a rate that doesn't flex the blade any more than is necessary yet is not so slow that friction from the blade burns the material.

Gill
 

dedee

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Steve,

I can't add anything to what Gill has said about blades etc - I am using the ones sold by Hegner (reverse tooth) and I have no complaints.

As for plans. You can have a lot of fun playing with MS Clip Art and the myriad of fonts available on MS Word. Photocopying the odd library book is also a useful source.



Andy
 

Gill

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Hi Roger

Variable speed can be very useful, especially if you want to do some very fine work. Generally speaking, the finer the work, the slower the speed.

I don't know anything about home-made variable speed controls. I'm completely out of my depth when it comes to training those pesky wiggly amps :) . In theory, I suppose it must be possible to make your own but I've no intention of trying it myself.

Gill
 
A

Anonymous

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Hi,

welcome to the fascinating world of scroll saw!

Stright lines can be almost like machine made. It's no merit at all, anybody can do it. Yours will be like that sooner than you think. It is only a question of practice. Just take some scrap wood and spend some time getting the feel.

I have a free pattern of a fruit basket in my site, quite simple to make and very good for practice. You could give it a try.

Pedro.
 

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