Hey all, I want to build a scraper to learn something new. Does anyone have any experience building one from Home Depot or a paint store odds and ends or something?
There must be a simple, inexpensive, quick way of getting going. If I find it meditating then maybe I'll splurge for a proper scraper down the road and just walk around the house and scrape stuff.
When I made my Gingery Lathe I took a file and ground away the file part and squared the end to give me a sharp scraper edge. Then scraped the aluminum castings with it. And some of the CRS of the ways.
Since then I bought 3 different scrapers from Busy Bee I think. One straight, one curved and one cupped.
PA sells them - the carbide comes square ground but it's easy enough to grind a slight rake and convex face. I think I paid $12 and it's as good as any I've used. It works well for light, close-up work where you don't need muscles.
Here is a pair of the same Titans that @Arbutus mentioned but from Amazon. One large and one small. I have a similar pair but I forget where I got them. Two for a bit more money than one at PA but delivered to your Door free with prime.
If a Biax isn't in the works, here's the next best thing....... (sorry but I don't think Amazon ones would be much good, too short, you need a bit of flex in it)
I've heard many talking about attempting to make a power scraper but I've not seen one report back that it worked. Maybe you'll be the first (please take lots of photos), however tons of machines have been done with hand scrapers. I have a biax and still usually finish with hand scraper. Its slower, but also somewhat less tiring as the biax is heavy.
All the above are bits of carbide silver solder to a shank and then a file handle is installed. Its really worth it to make them out of carbide. Make a bunch as its nicer being able to sharpen a batch then work your way through them.....they need constant sharpening. Cutting angle is about 92 - 93 degrees, else it can dig in its a misery.
Next up, sharpening. Your DOC when scraping is about a tenth of a thou. As such, it needs an extremely fine edge or it will just bounce over the surface. The way to do this is with cast iron wheel and 10 micron diamond paste. Lap the sides of the carbide to a mirror before silver soldering, then you just touch up the end on the diamond lap.
The laps have a taper mount (like a lathe) on hubs turned in situ on the shaft. This ensures next to no vibration. A crappy tire cheapo grinder and two cast iron disks.
After a few decades of of doing this, imo the above should save you a lot of heart ache.
Simple hand tools and simple principals let you achieve new factory (or better) precision, kind of like magical lol.
I just recently bought a scraper my self off FB. as I'm a frugle and don't mind spending lots of hours to make somthing nice. Haven't done much real scraping yet but I got few projects I want to use it on.
You can also use a small air grinder with zip cut to do "scraping" it works pretty good if you have good wrists and light touch and can be fast way of roughing and is common on glass hard ways and I think any "scrapped" machine that comes from China is done with grinder now a days.
I used air grinder to fix a the carriage fit on my buddies brand new Chinese lathe that he bought off island that was left outside in crate for a while. And I have to say there was like 20lbs of casting grit by time we finished cleaning and there was giant blow hole in carriage way that we filled with epoxy as you could hide you thumb in it. Should of toke some pictures of what we found while making it useable again.
@Mcgyver I like your bench grinder set up did you change the RPM at all or did it work fine as is? Ps. Also would love to pick your Brain when I start working on the c10mb project. I plan on rebuilding some of the carriage so I can maybe cut 3 feet out of middle of lathe.
No speed change, diamond on carbide does not need to be run slowly. Go as fast you can. People to seem to think diamond should be run slowly, but imo its kind of BS. Comes from those slow Glendo machines ....but they are slow so that 1) less diamond (carbon) gets adsorbed into the steel when sharpening steel, and 2) you don't effect the temper of carbon steel woodworking tools. No such restrictions with diamond on carbide.
@Mcgyver
Any recommendation for lapping paste? And do you just use the 10 micron stuff or do you have larger stuff for pre polish? I assume you do most of the roughing with a green stone?
Also do you think brass would work better then cast for making the wheels out of as my buddy bought small smelter and have good access to brass scrap.
I use a diamond wheel before lapping, don't like the green wheels......too much chipping. Diamond paste is sold everywhere, i.e. kbc, comes in a syringe. It goes a long way.
Brass will likely work although cast iron is the usual material. Its cheap, stable, takes the diamond well and damps vibration. The whole idea of the lap is that it is a cutting tool; the abrasive is pressed into the surface and work never touches the substrate; its ground away from contact with the diamond, so in theory it should work. I've used hunks of AL before to lap the flat sides of the carbide and it worked well.
FYI, this scraper from Grainger is not allowed to be sold in Canada. (At least when I wanted to buy it 2-3 years ago). The US government has prohibited the export of this item into Canada. Even though the Grainger.ca website lists it as for sale… I went all the way to Grainger HQ to try and find out why. No other reason than: ”it is prohibited by the US. Sorry Sir”.
So I made my own - still need a handle on each and a diamond sharpening device…
On the idea of spot grinding, not a fan, or at least I have my doubts as to how well it will work. Why scraping works so well is the very limited depth of cut. After a gabillion iterations, all is flat, from high to low, within a tenth. What variance between high low are you going to get after working it with a die grinder? In tribology, the bearing surfaces float on a thin wedge oil. if the variation from high to low is greater than the oil film thickness, I'm thinking its going be stalagmite colliding with stalagmite leading to rapid wear.
If you ran a tenths indicator over the surface it would probably provide the answer
FYI, this scraper from Grainger is not allowed to be sold in Canada. (At least when I wanted to buy it 2-3 years ago). The US government has prohibited the export of this item into Canada.
Interesting that good to know. Curious how the fellow in Ontario got hands on brand new one then. Also nice Babbitt scraper set I tried to get a set from person in Vancouver but wasn't interested in shipping so gave up on it as I don't have that much use for it currently just thought it was cheap enough to have sit around.
On the idea of spot grinding, not a fan, or at least I have my doubts as to how well it will work. Why scraping works so well is the very limited depth of cut. After a gabillion iterations, all is flat, from high to low, within a tenth. What variance between high low are you going to get after working it with a die grinder?
If you ran a tenths indicator over the surface it would probably provide the answer
The depth can be controlled pretty well when I played with you can do as light or heavy as one wishes. I'll do up test piece when I'm back from work and measure it with thenths indicator. The one thing I did notice is you get a square "scrape mark" or can do tear drop depending how you flick wrist. Probly can even do moore pattern if you use small disc and use the edge of disc but wouldn't be the same by any means
Not saying grinder "scraping" is the new end all be all. Just that it's a cheap way to make somthing flat as it's kinda like a Timex vs Rolex both tell time when you boil them down to basic function.
I also believe the gibs on my milling machine were grinder "scrapped" aswell because when i was messing around with it i was getting similar too what I remember seeing on my gibs. It has more crude flat edges compared to hand scraping were it is rounded and softer features much more refined.
Hey all, I want to build a scraper to learn something new. Does anyone have any experience building one from Home Depot or a paint store odds and ends or something?
There must be a simple, inexpensive, quick way of getting going. If I find it meditating then maybe I'll splurge for a proper scraper down the road and just walk around the house and scrape stuff.
The depth can be controlled pretty well when I played with you can do as light or heavy as one wishes. I'll do up test piece when I'm back from work and measure it with thenths indicator.
I'm going to be curious what your DTI tells you when you've lightly hand ground it. I'm not sure if this is the right way to even guestimate best possible or not, maybe @Mcgyver can weigh in. But I'm visualizing kissing a surface with a 400# abrasive, roughly equivalent to a spark out on a surface grinder wheel? Chart says the scratches would be 30 microns dictated by the particle size alone (Y=log scale). 30 microns is 0.0012" = 10X the 0.0001" removal of scraping pass. And hand grinder wheels are probably coarser? And your arm is not supported on angular contact bearings LOL. But hey, nothing ventured, nothing gained! I think some of the deep-ish markings you see on bed ways is oil retention scraping, which are micro channels superimposed over an ideally very flat (ground and/or scraped) surface made previously. But maybe smarter people can weigh in.
Chart says the scratches would be 30 microns dictated by the particle size alone (Y=log scale). 30 microns is 0.0012" = 10X the 0.0001" removal of scraping pass. And hand grinder wheels are probably coarser? And your arm is not supported on angular contact bearings LOL. But hey, nothing ventured, nothing gained!
Thats kinda neat chart I'm 99% positive I cant do .0001 with grinder, but I don't think it's unrealistic to get in the .0004 to .0009 range and Im interested in seeing for myself what can be done. As i didn't measure the "scraping" that I did on the carriage more so blued it for contact and measured how much of a banana (.009) the Chinese factory worker left after they fit the carriage to the bed. The carriage only touched in 3 spots and it was pretty bad. Was able to get to touch in 4 corners and more proper bearing then what they had left. So probly made the lathe 10% better in Grand scheme of things lol. It would take a lot of re work to make it a nice lathe. So I caution anyone who is interested in ording a lathe that looks like this from China especially for the lowest price. As depending on how much you spend kinda dictates quality between the same lathes.
I wouldn't recommend using grinder on surface grinder but probly fine on a 22" swing engine lathe but also depends on what the realistic capabilities of the equipment could do in first place and what you want it to do after.
Also @opensourcefan sorry I didn't mean to high jack your post and hopefully I didn't get too much in the way of the information that you were seeking in the first place.
The bearing scrapers are not often seen now, I believe I have a few that were my great uncles and have seen some use. I have some very hard? material that is on some implement feet, just have to figure out what to do, and how to remove it, as the metal it attached to is also hard and tough.
Project #, dam can't remember!
I have a set of those cheap bearing scrapers. I cut the HSS tip off the flat scraper and used it to make a pull scraper for the one awkwardly positioned way on my hendey carriage. It works well but does need frequent sharpening. Sharpening a HSS pull scraper bit is really easy with an oil stone though.
The push scraper I like the best I made with 3/16” x 1-1/4” (I think) cold rolled flat bar. Cut one end up for a file handle and made a little clamp for carbide bits on the other. I was given a couple of the square sandvik bits and with a clamp style attachment you can flip it and turn it to get a fresh edge. Those bits are pretty expensive though.
You can get small blanks from KBC at a pretty reasonable price that are good for soldering.
