Another home-made power scraper

[jhovel]

After reading lots about power scrapers here and elsewhere, I really liked the "sawzall" adaptation described in one of the past threads - that I can't find any more....
I needed to buy a cheap chinese reciprocating saw for a renovation job - and am unlikely to use it much in the future.
So I opened it up, modified the stroke down to 8mm (all reversible if needed) by drilling and tapping a new hole in the drive gear which produces the reciprocating action, and refitting the little needle roller bearing which drives the reciprocating slide.
I then made a scaper blade (more like a scraper 'lump' actually) from 3/4" mild steel, with a tungsten carbide strip brazed to one end. The fitting at the power tool end is a milled 1/2 wide slot, to get the blade facing the right way (unlike the previous builder who chose to hold the powertool on its side).

Since I have never used - or even seen - a Biax, I have nothing to compare my tool to. It works like a charm!
Pushed, it really makes the cast iron dust fly. Just gently held in position, it makes nice gentle scrapes, just as I would with my hand scaper. Only it is not exhausting and very quick. I use it at speed 2 out of 6.
I took me a little while to learn what angle to hold it at, so it doesn't jar my arm - and make gauges in the surface - and not skate across the iron.
It's pretty ovbious though and quickly learnt.
Anyway, here are a couple of photos of my effort:

[toughtool]

Joe,
That is a great idea, and just when the current Home Shop Machinist has an article about scraping. I will take a look at modifying mine and give it a try. I think I want to scrape bearing surfaces on some 3"X3"X1/4" steel tubing I plan on using for the X (and maybe) Y axis rail on my next CNC machine build. I'm currently using 1 inch (25mm) round crs but want something with less flex. Scraping 32 linear feet (four sides on two pieces of four feet long pieces) just for the X axis seemed daunting to me, since I haven't scraped before. Thanks for the idea. Joe

[Karl_T]

Ditto, what an elegant solution. Thanks for the great tip.

Karl

[jhovel]

Thanks guys!
Just remember, this is NOT my idea. I found it on this forum - I wish I could find the thread and acknowledge the right person. He copped a fair bit of flac from some members at the time.... but I thought it was an elegant solution. He machined a dovetail slide into the drive gear and made the stroke infinitely adjustable. I don't have the means to do that.....
Here are some of the photos which "made me do it" - that might trigger someone's memory so I can thank the original writer for his work:

[AFAIK]

Is this the thread?:

Power scraping. Anyone tried to convert a Makita HK0500 for metal? - Page 2 - Practical Machinist - Largest Manufacturing Technology Forum on the Web

Pictures start on page 2

[jhovel]

YES! That's the thread..... damn old age I woould have sworn I read it here....
Anyway, it was Mike (Holescreek) I have to thank! I'll post photos of mine in his thread to thank him...
When I finished reading the thread tonight, I noticed that he eventually reduced the stroke to 1/8" and found it better to control than the initial longer stroke. I'll try that next.
Here is a video link of him using his "Scaperzall":