Document X7kYyqMavkqwdmZB2ZLow8yDG
FILE NAME: Asbestos Cement Pipe and Sheet (ACPS)
DATE: 1978 Nov9
DOC#: ACPS034
DOCUMENT DESCRIPTION: Unpublished Report - Johns-Manville - Circular Saw for Dry-Cutting Corrugated A/C Sheet
m Johns-Manville
Research and Development Center
Report No. E411-1063
Date
November 9, 1978
Title:
CIRCULAR SAW f o r d r y -c u t t i n g c o r r u g a t e d a /c s h e e t SUMMARY
A shield has been developed for a standard portable circular saw (Rockwell Model 368-1), which allows corrugated asbestos-cement sheet to be cut dry In an acceptably dust free manner. The shield, illustrated In the Appendix, consists of upper and lower cases which enclose the blade and cutting zone. Each case Is connected to a vacuum source (Nllflsk GA73 vacuum cleaner) by 1-inch hoses. The shield works on the principle of near total enclosure of the cutting zone, to maximize the use of the available vacuum to retain dust within the enclosure and thus allow its removal.
The difficulty in enclosing the cutting zone when cutting corrugated, compared to flat sheet, is that the undulating surface presented to the blade is constantly changing. To achieve enclosure of the cutting zone, the "valleys" between corrugation crests must be blocked off to minimize air ingress, both above and below the sheet. However, the structure which blocks the "valleys" must be able to rise out of the depressions and over the crests. Additionally, the saw must be easy to use, l.e., the shield cannot "drag" on the sheet and require excessive force to operate. To solve these problems, overlapping rubber strips were placed on each side of the upper and lower cases. As the saw moves across the sheet, the strips extend into the "valleys" and effectively fill them to exclude air from the shield. They fold outward when a crest is encountered.
Tests using a common masonry blade (Table 1) in the "dust chamber" show that with no shield or dust collection, the dust count was 60.4 f/cc. With the shield, but with no rubber skirt, the count was 2.0 f/cc. There were substantial visible emmissions of dust during this test, and this fiber count is questionnably low. With the skirt, counts of 0.0 to 0.6 f/cc were attained, illustrating the effect of the device. Tested in an open room, the maximum fiber count was<0.1 f/cc.
It is concluded that this shield allows the cutting of corrugated asbestos-
cement sheet with a circular saw, equipped with a common masonry blade,
with fiber counts well under the 2.0 f/cc TLV. Cutting may be done across,
with, or diagonal to the corrugations. It is believed that this device will
be particularly useful to the medium and large contractor, on jobs whe^D/Jp*..
a substantial amount of cutting or trimming is required.
'
JH Contents: Summary, Appendix
Reported by JL. F. M. Bodj^iffib Asbestos & Mineral Technology
Reported by
R
G. R. Bauman Asbestos & Mineral Technology lkh
/
/. Pmulsack
- t-03 (S)
J J . DeBiase
- 3-15 (S)
/ Harris
- 2-12 (S)
/ Poutiatine
- 2-14
yu. Connor
- 2-14
J. Reis,
- 2-14
' D. Kelleher
- 2-14
R. M. Krone
- 2-20
L. Siebert
- 2-14
x E. M. Fenner
- 1-06
W. B. Reitze
- 1-06
G. L. Swallow
- 1-06
J. V. Magee
- 2-10
J. W. McLain
- 2-20
J. F. Leinweber
- 1-06
R. Kotin
- 1-06
R. E. Loeffler
- 1-04
J. Laipenieks
- 1-05
H. B. Moreno
- 3-14 (S)
A. L. Cini
- 3-14 (S)
F. E. Schlachter - Wertheim
G. Jacobs
- Mol
F. Colin
- Mol
J. Vandenbergh
- Mol
J. R. M. Hutcheson - Asb
R. E. Sampson
- Asb
A. R. Dennis
- Asb
E. J. Day
- Asb
M. D. Webb
- Asb
E. B. McKenna
- Asb
R. B. Gresham
- Asb
H. M. Hay
- Asb
KEYWORDS
.
Asbestos
Asbestos-Cement
Fabrication
Dust
Dust Collection
Environmental Health
w. C. srrc-lh W..J. Plichta D. R. Christensen A. Schnabel F. M. Bodycomb (2) G. R. Bauman (2) R&D Infomation Cen
,
PRODUCED
JM *S3
SAW & SHIELD FOR CORRUGATED A /C
REPORT NO E 4 1 1 -1 0 6 3
PAGE
2
7 1/2'
7 1/2' ------------->
<------------- 6 ' ---------------- ---------------- 6'
ZJkil Jo h n s-M a n ville Research and Development Center
Report No. E411-1063
Page
3
APPENDIX FIGURE I CIRCULAR SAW FOR CUTTING CORRUGATED A/C SHEET
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A irflow :
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1 80
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JM S3
IZ\ Johns-Manville
Research and Development Center
Report No. EA11-1063
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APPENDIX FIGURE 2
CIRCULAR SAW FOR CUTTING CORRUCATED A/C SHEET
f
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PRODUCED
JM.83