# Homebrew Power Scraper



## petertha (Oct 26, 2017)

Or maybe this should be 'what exactly is inside a Biax'?. Forgive my ignorance but I suspect will never be one of those lucky guys who own a power scraper. New ones like the BL-10 go for <cough> 3200$U. Used ones.. I rarely see on ebay anymore, they get snapped up quickly because people know what they are worth. I know, some of you will say just buy the hand scraping tools, and I probably will when I embark on a few simple projects. 

But I just wanted to explore - what makes these power units so expensive? Super accurate mechanism, heavy duty tool meant to last a lifetime, or maybe extremely low customer base even offshore replicators don't want to clone them? I see they have adjustable stroke length and controllable stroke rate. They look like big amp motors that convert rotary to linear motion. But what else? Seems to me as a qualified Youtube observer expert   that so much of power scraping is a hand/feel thing. For example, here are the guts of some random $200 Sawzall. Why couldn't we repurpose these mechanics, attach a good quality scraper blade assembly & accomplish something similar? Am I completely naïve & off base? If so, why?


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## Kernbigo (Oct 26, 2017)

it has already been done just google it, years ago


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## 4GSR (Oct 26, 2017)

The problem with the Sawzall is controlling the length of the stroke.  If you could vary the stroke length, you would have a much cheaper Biax!
I think it can be done.


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## Bob Korves (Oct 27, 2017)

The Sawzall handle setup is also not configured well for holding the scraper reliably level and for making tiny angle changes (steeper or shallower attack angle, precise left to right and right to left roll angles) to make the ideal cut for both hard and soft materials, and roughing and finishing passes.  We want to hit a precise spot on the work with a particular point on the cutter, making the length and depth of cut exactly what we want, and it varies during the pass.  Actually, a Sawzall works in a manner that is not very much like a Biax at all, though I sure would like to see a cheaper (and hopefully better) solution as well.  For me, so far, I have much difficulty getting the type of finished work I want with my ancient Biax.  I am tightening up the slides of it presently, and hope that and lots more practice will give me better results.


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## petertha (Oct 27, 2017)

Hmm..I tried some different keywords. Most of my initial searches turned up rather non-applicable contraptions. This looks interesting, but you guys have raised some worthwhile points.


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## petertha (Oct 27, 2017)

Sorry, just had a bugger of a time trying to respond to this post. Repaid my subscription, changed my password, logged on & off, tried contacting Admin... I thought maybe embedded link. Something tells me it had something to do with the little gear symbol? I'll tinker around a bit & try & find that link.

Anyway, thanks for good points & comments. I guess hand scarping is in my future


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## Ulma Doctor (Oct 27, 2017)

the reason, IMO, the biax is so expensive is that there is a lot of costs involved with presenting small numbers of precision tools to a select base of people. you add the dealer mark up, the freight to get them from europe to the US, and other costs not covered- you soon have an initial manufacturing and delivery price that is high.
they are wonderfully crafted and very durable.
not to discourage but, i would find it difficult to imagine creating a machine from another machine that could come close to performing the same action as accurately as the biax.
the machine of new creation may perform the same function, but it may not give the same final result in the same amount of time.
the engineers that made the biax were very good at their job.


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## Sblack (Oct 27, 2017)

looking at my worn out biax I see how robust it is. The shoe that carries the blade is forged and it rides on lapped tool steel ways (probably D2 which has low friction). The ram runs in a bushing. it is a high quality motor housing. the body is a heavy casting that is comfortable to hold. These things can run all day for years. They are made in Europe for industry, and industry wants something good.  They care way more about down time than the initial cost. Who cares about $2000 for a tool. If it breaks and some guy sits around for 2 days there's your $2k right there .Also they don't sell the quantities that they do with consumer products.


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## Kernbigo (Oct 27, 2017)

the bia i used i think was made in germany or switzerland


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## 4GSR (Oct 27, 2017)

Kernbigo said:


> the bia i used i think was made in germany or switzerland


They are made in Switzerland.  Over on the other forum, Richard King shared some pictures of the place in Switzerland that makes and assembles the Biax power scraper.  Oh, I believe the motor assembly is made in Italy by a well known power tool company.  Can't recall the name.


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## brino (Oct 27, 2017)

Here's one from this site:
http://www.hobby-machinist.com/threads/home-made-power-scraper.18945/#post-158171
it does have an adjustable stroke!
-brino


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## Ulma Doctor (Oct 27, 2017)

brino said:


> Here's one from this site:
> http://www.hobby-machinist.com/threads/home-made-power-scraper.18945/#post-158171
> it does have an adjustable stroke!
> -brino


he did a nice conversion, and it worked for his purposes.
it would beat the crud out of hand scraping large surfaces!


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## Bob Korves (Oct 28, 2017)

I really think there are several overlapping concerns here, all with trade offs.  

Yes, a Biax scraper can get VERY expensive.  I got my ancient one from Ulma Doctor for an extremely fair price.    On eBay, most sellers are not as nice as Mike is, to say the least...  So one approach is to simply wait for a good deal to come along.  I do this a lot, but I notice that most of us get on a kick and want to be running with it NOW!   Damn the cost and learning the options and the market!  Often, mistakes are made, some expensive.  I try hard not to do that.

One regularly seen approach is to show the ba$tards that one can be made for next to nothing using stuff laying around in dumpsters or modding a HF tool.  Good idea, can allow for quick prototype builds with little investment of time and money.  The down side is that quick and dirty does not usually give us the elegant 'does everything exactly the way I want it to and will last forever' qualities that we would also like to see. Been there, done that.  Quick and dirty can require multiple resets, starting over from scratch again.  After a few tries, the project is often abandoned.

Another common approach is trying to build the PERFECT power scraper, with all the bells and whistles, NASA grade components, ergonomic studies, pretty CAD drawings, finite element analysis (FEA), torture testing to failure, built in floodlights, video camera, electronic leveling readouts -- well, you get the idea.  It will never be finished, and will cost many times more than a new Biax by the time it is only partially functional and is abandoned.  Been there, done that, too...

All this is to say that I think we need to strive for a simpler and better answer.  The more people working on it, and posting their success and failures, the better.  In a tiny niche market like this, we need to create any improvements to the craft, because industry does not give a damn about us, no money to be made.  Work on it, keep working on it, and let us know how you are doing, and what works and what does not.  Collaboration is a powerful tool...


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## petertha (Oct 28, 2017)

Here is the link I originally intended to post
http://www.practicalmachinist.com/vb/general/my-home-made-power-scraper-236293/


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## Kernbigo (Oct 29, 2017)

after converting a sawzall to a scraper i would also bend the cutting toll 90 degrees i think it would work better


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## TakeDeadAim (Nov 20, 2017)

In looking at the pics of the Skill recip saw scraper the maker did figure out how to adjust stroke length.  I think was is missing is the heavy duty support the Biax has in the front end.  The plus of the power scraper is the ability to take off more metal quickly.  That requires pushing down pretty hard on the tool.  I'm not sure I see the same support in the front of that recip saw that is in a biax.  Might work well for power flaking.

What I don't like about the any of the power scrapers is the finish they leave compared to hand scraping.  IF and only if you push your scraper with the hip rather than holding it in the hands you can accomplish some pretty good material removal.  My former employers did not allow power scrapers so I know first hand the effort involved in hand scraping a large area.  Fortunately for us hobby machine sizes are not large areas and can be accomplished by hand.  Unfortunately somewhere along about back surgery number 2 of 4 my ability to push much of anything has decreased.  Fun to break open the tool box full of handles and remember better times though.


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## Susan_in_SF (Feb 17, 2020)

As for adjusting stroke length on a converted Sawzall, maybe it could be done if there were a way to change out the scraper end.  Kind of like how you can change ends with a drill or impact driver.  Just a thought.  I haven't looked at the referenced Sawzall conversion thread yet.
Then again, maybe thanking ends wouldn't change stroke length at all :-(
Darn!


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## Kernbigo (Feb 17, 2020)

I just made a new power scraper like none has done before. I may market it, it is 4 the hobby machinist only to small 4 commercial use. It is smaller than a biax but works good. I'm using a carbide tool as the cutter, sharpened at 5 deg. Negative. 

Sent from my SM-G970U1 using Tapatalk


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## middle.road (Feb 18, 2020)

Kernbigo said:


> I just made a new power scraper like none has done before. I may market it, it is 4 the hobby machinist only to small 4 commercial use. It is smaller than a biax but works good. I'm using a carbide tool as the cutter, sharpened at 5 deg. Negative.
> 
> Sent from my SM-G970U1 using Tapatalk


Can't wait to see it someday.


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