DIY Electric scraper

[Graham Stabler]

I started looking in to this and then saw a not so well advertised unit on Ebay and won it for just under £200 quid, it's one of the older blue cylindrical types with some blades although mostly big flat ones.

But I will share what I found and my ideas because who knows how long it will last and it's all good fun anyway.

What's inside a Biax:
Biax 7EL assembly/repair:

For some pictures of the assembly.

And here is the patent for the variable stroke drive: https://patents.google.com/patent/US2940324A/en

It's a relatively simple mechanism, the adjustment changes the angle of bearing with respect to the axis and a connecting rod with bearings couples this to the output which is constrained suitably with a linear bearing or way.

Fundamentally you need a motor, gearbox and this mechanism.

Inspired by this angle drill which is clearly an add on:Makita angle drill

I suggest a geared drill with metal body, remove the chuck and clamp scraping doodad where the handle normally goes. Something like:

Makita rotary drill

It has a max rpm of 1200 which is lower than a biax but OK I think and the weight leaves some overhead for the mechanism, ergonomics might not be ideal but not sure. I imagine a DIYer could live with it or get the saw out.

Cheers,

Graham

[Joules]

Or build it just like a shaper bull wheel, perhaps using a cross shaft with right and left hand threads so you can wind a counterbalance out with the stroke adjuster.

[Peter Cordell]

I did see a post some time back about converting a sawzall I bought reciprocating saw just not had time to try and mod it

[Graham Stabler]

The nice thing about Biax's invention is that it is compact in length and everything that moves has a bearing, no rubbing scotch yokes etc. Mini-shaper is OK but ends up being longer I think, also needs that direction change, so bevel gears or an angle drill.

There are some converted saw videos on Youtube. They seem to work.

I'd rather come up with a design that can be modified and fitted onto the rotary power source of the builders choice.

Cheers,

Graham

[Joules]

Why not go the whole hog and make it pneumatic.  Adjustable end stops, one moving part other than valve components.  You could almost build it into a hand scraper sized device.  The engraving world has had these devices for years.

[Pete.]

The Biax is sublimely clever in it's simplicity. The globe-shaped stroke adjuster is inherently balanced regardless of what stroke is set so the only reciprocal reaction is from the fairly lightweight shaft, clamp and blade.

Let's have some photos of your bl7 then Graham

[mm289]

I started looking in to this and then saw a not so well advertised unit on Ebay and won it for just under £200 quid, it's one of the older blue cylindrical types with some blades although mostly big flat ones.

I'm not jealous 

Paul 

[Graham Stabler]

I won't get it until new year but intend to strip down and service so will photo the heck out of it. Sorry Paul but you are welcome to borrow it

I also asked Thang from a channel I use for mechanical inspiration if he would consider drawing up the mechanism from the Patent, and he did:

[embed=425,349]<iframe width="560" height="315" src="

" frameborder="0" gesture="media" allow="encrypted-media" allowfullscreen></iframe>[/embed]

The real deal does not use a ball joint but otherwise it shows how it works nicely.

Cheers,

Graham

[j1312v]

Hi everyone,

I found this link the other day showing a rather cleaver and well engineered DIY scraper  http://www.die-minilok.de/Werkstatt/Schaber.htm ...enjoy


Best,

B

[Graham Stabler]

Interesting, the inside of the saw he modified uses the same basic mechanism as the Biax only not adjustable so he made a new crank, still not adjustable but better than nothing.

Graham

[Joules]

Neat solution, just needs better bearing surfaces, change angle sleeves for different travel.