changing blades

[pilar]

I'm borrowing an older (i think) 15" Delta scroll saw for a weekend project, and can't figure out how to put a blade in!

I used an allen wrench to loosen the screw, but tried to tighten a blade in there, and I can't tighten it so it's even remotely tight... What am I missing?? Unfortunately it didn't come with a manual..

Any help for a very new beginner would be appreciated!! Thanks!

Pilar

[GrayBeard Phil]

Pilar:

This is difficult to answer because it is mostly a written media. If I was there, I could show you in 10 seconds flat. But instead I must use a lot of words to describe what could be causing the problem.

Delta scroll saws of about 10 years old have an older style blade chuck that used a hex key tool. The blade chuck worked like a square threaded nut that got tightened against a fixed blade plate. The hex bolt went thru the blade plate and drew the nut tight against the plate.

The plate was special because in the back there was a small raised section of about 0.100 inches. This, at least in my way of thinking, was because the most common blades, #5 and #7, are about that same thickness, and thus the nut would exert pressure even and flat against the blade.

However, if you used a blade of say #3, #1 or smaller, one had to learn by trail and error to be sure to place the blade not in the center near the hex bolt but closer to the front of the blade chuck. The nut would tighten at an angle on small blades because of the raised part behind the threaded bolt.

You have to do this for both the top and bottom blade chucks. The additional problem is oil and rust prevention coating from the blade factory. These would cause the blade to slip out of this Delta blade chuck. The new Delta machines use a different type of blade chuck that you can get at Amazon.com (and elsewhere) for about $25.00.

There is another mechanism that is used to apply blade tension, a lever that is rotated to the back of the saw to apply tension. but you didn't mention a problem with applying tension. Just having problem of fixing the blade into the chuck and having the blade chuck hold the blade securely.

Do check to make sure the threaded bolt has not been stripped. Remove the bolt and the square nut, and run the nut all the way up and down the bolt to insure there is no binding what so ever on the threads. The bolt threads do stretch and distort. In a pinch a real hardware store can replace the hex bolt with something else as long as it thread into the nut all the way just using your hands.

Hope this Helps

Phil

PS: Do come back and chat, I know you are stessed out for your project, so I will hold off on the greetings bit.

[GrayBeard Phil]

Pilar:

I forgot to add, that sawdust in the threads and the nut can cause problems. When you remove the bolt to check for thread problems also look for any saw dust.

Phil

[pilar]

Hi, thanks for your speedy reply. I think the problem was that the size of the hex key... could it be a metric size?

I was using a 7/64" hex key which was slightly too small (the next size up too big) and wasn't able to tighten it enough.

Now I'm using a combination of a "star" screw driver (don't know what it's called) and some needle nose pliers. Seems to do the trick!

I will now read the thread about tension... because that blade just broke!

Thanks again. I will definitely be back. Besides the technical setting up issues, I really enjoy using a scroll saw.

[Gill]

It's not just tension that makes blades break; oh, if only it was that simple!

Expect to break some blades whilst you're learning. As well as blade tension you need to consider the size and type of blade, the type and thickness of wood, the number of strokes per minute, the feed rate, the tightness of turn, the longevity of the blade and probably quite a few other aspects that other people will mention .

What I'm saying is that experience counts for a lot in this game. You'll continue breaking blades until the time you realise you aren't. By then, of course, you'll have quite a smug grin on your face and lots of masterpieces to display.

Gill

[GrayBeard Phil]

Delta Blade Wrech 1343648

Ah, yes the missing special wrench. As I said, 10 seconds if I could see your saw.

Per the parts drawing of my old Delta, that bolt is a M5 X 10mm long bolt. M5 hex head bolts need a metric 4mm hex key.

If you look on the upper arm, just above the blade chuck M5 bolt there is a small hole a bit larger than 3/16 inch (it really is about 5mm.) The special wrench, Delta part number 1343648, had the hex key attached to a steel rod. The rod was fixed and the 4mm hex key rotated. You inserted the rod into the hole to stabilize the pivoting blade chuck. Thus the force you applied to torque down the bolt was applied to the head of the bolt not in moving the blade chuck.

The hole for the rod on the lower arm is of course below the lower blade chuck.

If you have a dull 3/16 inch drill bit, you could insert that into the locking hole to make it easier to tighten the blade chuck. Use the back end of the drill bit, where it is solid metal.

Be aware that you must tighten down that bolt with a good amount of force. (Don't go crazy and put 'your-back-into-it'.) The blade must have enough force on it to hold it in place without slippage. Any blade slippage will result in blade breakage. The cutting of wood will apply a resistance force on the blade.

Please keep in mind, scroll sawing is a skill. It is an easy skill to learn, and it isn't hard, but all skills take practice. It is an eye-hand type of thing. We all mostly just free hand the wood past the cutting blade. There are many factors that affect excessive blade breakage, I have tried to explain just a single one. Please re-read our friend Gill's post on this thread.

Phil

[Mick Walker]

Yes, Phil is right, you need a special wrench as Phil described for the older Delta saws. I had the older 20" VS Delta. I switched the upper clamp to the newer Quickset II clamp but you can't switch the bottom clamp as there is not enough room under the table. I now have the P-20. Mick

[Neal Moore]

If you're breaking a lot of blades with that saw you might want to check the rubber bushing that is part of, I think, the blade tensioning assembly. I can't remember exactly where it's located but I do know they wear out, fall out, and/or become misaligned resulting in frequent blade breaks. I gave my delta away a long time ago and I can't remember the exact mechanics of the thing. Maybe one of the Delta owners can provide better info.