Clearance on shear blades?


We have an old 8 ft shear. Bersch is name on nameplate and when i last
tried to find any info i found nothing. I'm wondering about setting
the clearance for the blade. Its worked fine in the 3 years i've
worked here but we almost always only shear steel of 10ga and thicker.
I've cut a sheet of 1/4 and 8ft long with no trouble.
Now the boss is talking about shearing some sheets of 25 guage and
he's concerned it is too thin. I checked and found clearance to be
mostly around .004 and at far end it was down to .002. I've been told
some shears are not setup with equar clearance. So i'm wondering if
anyone has any general rules about shear blade clearance. I thought i
would hold off trying to get everything close to .002 till i saw if
anyone with some actual knowledge had any advice.
Rosco
Reply to
Butter
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Butter wrote in news:babfdfa1-6065-466d-9f31- snipped-for-privacy@m11g2000vbl.googlegroups.com:
I'm not sure about shears that large. The 12" & 24" DiAcro shears would typically cut newsprint cleanly with ease if they were sharp & not abused. That suggests clearance less than 0.002". I've certainly never had problems cutting 5 mil shim stock, even in some pretty battered ones.
Doug White
Reply to
Doug White
You must have a proper clearance for effective cutting. Too much or too little is bad. Rule of thumb is 5 to 8 percent of material thickness. Your 0.002" figure will thus cover about 0.020" to 0.050", which is a useful range for typical work. Adjust the tool to keep this all across the blade width, not just at the ends, but especially at the starting end.
Reply to
Richard J Kinch
You got me thinking. Why would the clearance be any different than on a die? If this is the case we've had too little clearance since it was set years ago. We do not use this shear very much and its only because the boss can't find anyone to buy it that its still here. Since after this upcoming job for this thin guage mateiaiwe'll be using it for the thinker steel i guess i need to then increase the clearance to acomodate this. Rosco
Reply to
Butter
formatting link
HTH,
Wes
Reply to
Wes
Thanks- This is exactly what i've needed Rosco
Reply to
Butter
Glad to have helped on a real on topic question.
Wes
Reply to
Wes
Tell me clearance in mm & for tickness of the material in mm also. Please.
Reply to
manikonar126
I presume that you have the shear with instructions which include clearances in thousandths of an inch, and thickness (not "tickness" as you asked) in either also thousandths of an inch, or as a gauge.
To convert thousandths of an inch to mm, you simply multiply by 25.4.
As for converting the gauge to a metric value, you will need a look-up chart. The only one which I happen to know directly (and which is a common maximum thickness of steel for hand operated shears) is 16 ga, which (mostly by accident) is very close to 1/16" of an inch, or 0.063" or 1.58 mm Larger gauges are thinner, so the match can only occur at one point.
The clearance values are likely somewhat different depending on the brand and model of shear -- and how strong it is.
The only mention for the DiAcro #12 and #24 shears is that the clearance is defined by the thickness of the blade, and if you grind it thinner, you will need to add shim stock to restore the thickness.
For the DiAcro #36 hand shear it says:
====================================================================== Blade clearance may be varied but for longer blade life, a few thousandths clearance should be maintained. Blades should not be in actual con- tact with each other. Best results may generally be obtained with .002" clearance on the ends and .001" clearance at the center. ======================================================================
And -- from the calculation above, 0.001" is 0.0254 mm, and 0.002" is 0.0508mm. And elsewhere, they mention that this setting should work from the thinnest metals to 16 ga (from above, about 1.5mm)
Good Luck, DoN.
Reply to
DoN. Nichols
"DoN. Nichols" fired this volley in news: snipped-for-privacy@Katana.d-and-d.com:
REALLY, Don?
First, you jab the guy for a simple typographical error, then you give an incorrect conversion to answer to his question?
LLoyd
Reply to
Lloyd E. Sponenburgh
"Lloyd E. Sponenburgh" fired this volley in news:XnsA32444593CC0Blloydspmindspringcom@216.168.3.70:
PS... you did the math right yourself, you just gave him the wrong conversion formula.
LS
Reply to
Lloyd E. Sponenburgh
Huh? Works for me.
0.040 x 25.4 = 1.016mm
Reply to
Kennedy
Thanks for catching that. I wonder how asleep I was at that point.
Enjoy, DoN.
Reply to
DoN. Nichols
O.K. Multiply the dimension in inches by 25.4. In the case of thousandths of an inch, I automatically use the decimal form (0.001" not 1").
As for the typo -- I wanted to make sure that he was really talking about a shear. At leat I know one meaning for shar (and it does not need clearances in any units. :-) But there may be other meanings too. I usually ignore typos if I understand what was meant, unless they could shift the meaning of the question.
Thanks for catching it, DoN.
Reply to
DoN. Nichols

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