Dodgy Saw Bench!

[vassilis]

I have a problem with my brilliant Scheppach saw bench which I bought in England about 20 years ago and now have with me in Greece, where I live.

It is the Prima TKV Nr 0184 B1984 with 12 inch TCT blade (rip and crosscut, black with no maker’s name, which I think was the original equipment, and which I took off the machine from time to time for setting and sharpening).

About three months ago I bought a new steel blade (30cm Siebel Line HARTMETALL) for fine woodcutting, keeping the old TCT blade for cutting melamine panels.

The Scheppach loved it, splinter-free easy cutting of soft and hard wood.

But….after about one month’s work, the blade came loose, flying up and crashing against the riving knife and blowing the mains electric trip switch.

I took the blade off and put it on again. It worked perfectly.

But yesterday the same thing happened without warning when I was in the middle of cutting some small softwood.

What is the answer? I understand that the left-hand thread on the motor plate acts as a self-tightener on the blade. Have I been fitting the new blade too tightly? Not tight enough? Or could there be some fault in the new blade? Or something else? I am afraid to use it until I know. Scheppach answered my query but not very adequately because of the language barrier. Any thoughts, anyone?

 

[Chris Knight]

Vassilis, welcome to the forum.

Can you weigh the two blades accurately? If your saw has an electric or other form of brake, it's possible that if your new blade is a heavier blade than you have been using previously, it will try to continue rotating when the shaft has stopped turning or is slowing down and with the extra weight, succeed in unscrewing the left hand threaded nut.

This happened to me when I first used a dado set on my Scheppach TS 4010. My saw has an electric brake and I was able to adjust it to reduce the braking effort which allowed me to use the saw safely.

 

[OllyK]

May sound a daft question, but the bore in the blades is the same size isn't it?

 

[Blister]

May sound a daft question, but the bore in the blades is the same size isn't it?

and the thickness of the blade where it bolts on ?

 

[maltrout512]

Vassilis, welcome to the forum. Sound like there is a problem, waterhead37 has an idea. Just jumping to dado blades they do say that they should not be used on a braked motor.!!!!. Anyway back to your problem. (Blister)The thickness of the blade could be the problem where it mounts onto the drive shaft. Too thin and the collar on the inside of the blade will protrude out too far and stop you from tightening the blade. don't take much about 2 thou will cause problems.

 

[vassilis]

Just wanted to say a very belated thank you (two weeks of computer problems, no internet!) to those who offered advice and helped me to get sorted with a combination of ideas.

I also thought you might be interested in the cost of hardware in Crete where I live. Today’s shopping list:
500 4mm x 50mm pozzidrive screws
500 4mm x 60mm pozzidrive screws
20 strong brass angle brackets 4 x 4cm
2 x 100g pots PVA adhesive
2 x WD40

Total bill: 21.40 euros which at today’s rate is about 18 quid. (A few months back you could have had that lot for nearer 13 quid, so you can tell that nice Mr Brown he didn’t know what he was missing when he held out against the euro)
Kali nixta!

Vassilis

PS AND the temperature today was 70 degrees F…….