45 degree
45 degree
(OP)
In a design for a scraper that is to skive off flooring, such as linoleum, tile etc, I am trying to prove that a 45 degree angled blade is the best choice for wear and capability. The blade will be flat to the floor and the leading edge is 45 degrees. Does anyone know how I can prove this to be true? Calculations or any other means would be very helpful. Thanks
Jim
Jim





RE: 45 degree
If you had say a 30 degree slope that would allow for more "shoving" or "pushing" power and maybe just enough "uplift" to break the bond. It does not take much to break the bond --- but obviousy depends on many unknowns...
Will this be power or man driven.
RE: 45 degree
<tg>
RE: 45 degree
Lets assume that the bonding of the material to be removed to be high also. If it were not, any angle would work (other than 90).
We can probably disregard the friction (although I realize it is there). I am trying to determine that when using the blade, the leading angle could be more or less than 45 degrees but to get a compromise between its wearability and its usefulness, 45 would be equally good for both.
Jim
RE: 45 degree
Bill
--------------------
"Why not the best?"
Jimmy Carter
RE: 45 degree
I would tend to go, floor to blade angle of 30° maximum.
You're trying to pry the linoleum/tile off the floor, not jack hammer it downwards. That's a whole different tool.
V
RE: 45 degree
RE: 45 degree
Griffy
RE: 45 degree
The underlying floor is generally concrete and the overlay can be just about anything. The blade is ridged enough (1/2" thick) to be considered ridged. The blade can ride up and over the overlay, on occasion.
I have read in the cutting tool section of Machinery's Handbook but the application isn't exactly the same. The blade I am working with sits flat on the floor and the 45 degree leading angle separates the overlay from the concrete.
I understand this may seem to be oversimplified with all of the variables present, but I had thought there may be some known rule or way to calculate edge wear and/or edge effectiveness, for knives, scrapers, chisels etc.
RE: 45 degree
From what little I've seen of these blades working I would go with a compound angle and let the wear go where it may.
htt
RE: 45 degree
It will probably matter also what flooring you're removing - is it flexible, ie, linoleum, or rigid, ie, tile?
RE: 45 degree
<tg>
RE: 45 degree
RE: 45 degree
TTFN
FAQ731-376: Eng-Tips.com Forum Policies
RE: 45 degree
You might be in for a surprise.
RE: 45 degree
The OP is not asking how to find the optimum angle, but how to prove that the existing angle is adequate.
"Good to know you got shoes to wear when you find the floor." - Robert Hunter
RE: 45 degree
Can't help you, because I don't think that's correct.
V
RE: 45 degree
<tg>
RE: 45 degree
RE: 45 degree
KENAT,
Have you reminded yourself of FAQ731-376: Eng-Tips.com Forum Policies recently, or taken a look at posting policies: http://eng-tips.com/market.cfm?
RE: 45 degree
You're almost as cynical as I am.
V
RE: 45 degree
KENAT,
Have you reminded yourself of FAQ731-376: Eng-Tips.com Forum Policies recently, or taken a look at posting policies: http://eng-tips.com/market.cfm?
RE: 45 degree
....
you need to get a new boss.
Tomorrow.
Mike Halloran
Pembroke Pines, FL, USA
RE: 45 degree
TTFN
FAQ731-376: Eng-Tips.com Forum Policies
RE: 45 degree
Try and find the truely optimum angle.
See how close 45 is to it.
Come up with some justification of why 45 is a reasonable approximation given other factors that can't easily be calculated or some such twaddle, or perhaps 45 is within X% of the theoretical ideal etc.
KENAT,
Have you reminded yourself of FAQ731-376: Eng-Tips.com Forum Policies recently, or taken a look at posting policies: http://eng-tips.com/market.cfm?
RE: 45 degree
This may muddy up the discussion but....
We all know that if the blade was 90 degrees it would not wear as much as the 45 degrees but the 90 would not lift the flooring. I think that line of thinking is why 45 degrees was chosen originally. (anything less than 45 would wear quicker too)
Thanks for the Archard Equation suggestion, I will see what I can do with it concerning the wear.
RE: 45 degree
RE: 45 degree
I suggest that optimum service life between sharpening and repair may not be the same as optimum for best efficiency and least energy expended.
Bill
--------------------
"Why not the best?"
Jimmy Carter
RE: 45 degree
Why not just check out the competition, i googled "floor scraper concrete" and came up with http://www.floor-equipment.com/
Ring them up and ask if you were to buy/rent how often you would have to change blades. Ask the operators of your equipment what sort of lifespan the blades have.
It may be there is no theoretical answer - how thick is the lino, is there more than one layer, what adhesive is used will surely all play a part. Older lino floors may have asbestos in them and may require you to apply special precautions to protect the operators.
Regards, HM
No more things should be presumed to exist than are absolutely necessary - William of Occam
RE: 45 degree
I did this about two years ago in order to take a lot of tile/linoleum off plywood subfloor. I bought a commercial scraper blade and reground it by trial and error.
I found the angle varied with the hardness of the glue. Hard glue required an angle above 35 degrees, but much higher dug into the plywood. Soft glue loosened well with something close to 30 degrees or a tad less.
I worked with the bevel down and found I needed a slight crown on the bevel so that I could "rock" the point up and down to avoid plowing - more of a problem with low angles.
I wound up doing a little bit on concrete and found that something like 45 - 50 degrees worked well since it didn't come to a dead stop every time I hit a concrete bump.
I think that if I had to do it again, I'd have tried pouring liquid nitrogen on the floor first to make all the glue brittle.
RE: 45 degree