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Evolution of Power Tools

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Forum topic by BDFan1981 posted 632 days ago 2248 views 0 times favorited 17 replies Add to Favorites Watch
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BDFan1981

96 posts in 957 days


632 days ago

Topic tags/keywords: power tools evolution design

You folks ever wanted to know about the evolution of that one particular power tool?

Examples of power tools with one model number that went through different design changes:
Skil 534 6-1/2” Saw = produced 1966-85, replaced by 5125 in late 1984. Originally 3-wire (grounded), motor was double insulated in late 1976 (type 8).

Evolutionary picture (from eBay):

(note the double-insulated version of the tool is the one that is torn apart)

Skil 574 7-1/4” Saw = produced 1966-85, replaced by 5150 in 4th qtr. 1984. Originally 3-wire (grounded), motor was double insulated in late 1976 (type 8).

Early version (brushed chrome motor housing):

Later version (dark gray motor housing; double insulated, 1976-77 production, UL symbol and warning text on nameplate instead of separate decals):

Much later version (note slightly different text design, 1977-82 production):

(this example was made in October 1981 going by the date code)

Final version (company city/state and specifications move to black portion of decal, 1982-84 production):

(this example was made in November 1982)

EDIT 1-18-2013: See changes.

~Ben


17 replies so far

View Handtooler's profile

Handtooler

1071 posts in 759 days


#1 posted 632 days ago

Very Interesting! You are sure on top of your game.

-- Russell Pitner Hixson, TN 37343 bassboy40@msn.com

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Purrmaster

777 posts in 720 days


#2 posted 632 days ago

Interesting. Did the specifications on the models change as well? Horsepower, amperage, etc?

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BDFan1981

96 posts in 957 days


#3 posted 632 days ago

Re: Purrmaster
Yes. Originally, the RPM was 5700 on the older versions (with the 3-wire cord), and the double-insulated motor versions (2-wire cord) had the motor rated down to 4600 RPM.

Ironically, however, on the box for the Type 6 version (3W cord) the RPM is 5700, when on the Type 7 version (again 3W cord) the RPM is 5300.
Picture 1:
Picture 2:

This is odd: the box says the machine is a Type 6, but the actual tool is a Type 7.

~Ben

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Surfside

3079 posts in 800 days


#4 posted 631 days ago

Excellent post!

-- "someone has to be wounded for others to be saved, someone has to sacrifice for others to feel happiness, someone has to die so others could live"

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BDFan1981

96 posts in 957 days


#5 posted 582 days ago

I want to let you folks know that Skil did not emboss the date code on the tool’s nameplate until late 1978. Before then, the date code could be found on a separate decal located elsewhere on the tool. These decals could get lost as the tool ages, so be sure to take good care of any of these pre-1979 Skil power tools which still have them to this day. The date code was also stamped on the box.

~Ben

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Purrmaster

777 posts in 720 days


#6 posted 582 days ago

Good information. Please keep it coming.

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BDFan1981

96 posts in 957 days


#7 posted 563 days ago

More: on some of their “Super Duty” or “Heavy Duty” circular saws (sidewinder design) the date code may instead be found on the decal applied to the upper blade guard.


(from a model 553 made 10/83)


(model 866 made 4/80, this one was really used and abused, so much that the main handle is broken)

~Ben

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runswithscissors

906 posts in 652 days


#8 posted 563 days ago

I am wondering if the rpm ratings were for the blade speed rather than motor speed. If so, would that indicate a difference in gearing (I don’t think any of those were/are direct drive)? Just curious.

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BDFan1981

96 posts in 957 days


#9 posted 563 days ago

I am not an expert there although I can point out the 6-1/2” blade size models do run at a slightly higher RPM than do the 7-1/4” units, and while most 8-1/4” units may run at the same motor speed as the 7-1/4” units, some others may have still reduced motor speeds, and the big 10-1/4” saws have a further reduction in motor speed to match the speed of the motor to the size of the blade in relation to the blade tip speed factor.

HEAVY DUTY SIDEWINDERS
552, 5625 = 6-1/2”, 5800 RPM = 9870 FPM
553, 5650 = 7-1/4”, 5200 RPM = 9870 FPM
554, 5665 = 8-1/4”, 5200 RPM = 11,231 FPM

DROP FOOT SIDEWINDERS
807, 5750 = 7-1/4”, 5800 RPM = 11,009 FPM
808, 5765 = 8-1/4”, 5800 RPM = 12,527 FPM
810, 5790 = 10-1/4”, 5200 RPM = 13,954 FPM

WORM DRIVE SAWS
367, 5825 = 6-1/2”, 4600 RPM = 7828 FPM
77 = 7-1/4”, 4400 RPM = 8351 FPM
825, 5865 = 8-1/4”, 4300 RPM = 9287 FPM

It should be noted that the worm-drive saws are geared much lower to deliver higher torque levels.

~Ben

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BDFan1981

96 posts in 957 days


#10 posted 538 days ago

I want to revive this thread as to point out the following about warning label texts:

In the year 1977, the specifications text looked like this, for example:
(black border)
SKILSAW® (trade name in red text)
7-1/4” Circular Saw
574
(red border)
120 Volts A.C. only – 25-60 Hz.
10 Amps – Type 8 – 4600 RPM
When servicing use only
identical replacement parts. (UL logo/Listed 293G text)
CAUTION: For safe
operation see manual.
SKIL CORPORATION
CHICAGO, ILLINOIS – Made in U.S.A.

It was stylized like this for 1978:
(black border)
SKILSAW® (trademark in red text)
7-1/4” Circular Saw
574
(red border)
120 Volts A.C. only – 25 to 60 Hz
10 Amps – Type 8 – 4600 RPM
CAUTION: FOR SAFE OPERATION SEE
MANUAL. WHEN SERVICING USE ONLY
IDENTICAL REPLACEMENT PARTS.
SKIL CORP. (UL symbol at right with “Listed” and “293G” on top and bottom of circle respectively)
Chicago, Ill. – Made in U.S.A.

It was then changed to look like this from 1979-81:
(black border)
SKILSAW® (trademark in red text)
7-1/4” Circular Saw
574 (UL symbol with “Listed” and “293G” at top and bottom of circle respectively)
(red border)
120 VOLTS – AC ONLY – 25-60 Hz
10 AMPS – TYPE 8 – 4600 RPM
CAUTION: For safe operation
see manual. When servicing use
only identical replacement parts.
SKIL CORP.
CHICAGO, ILL.
Made in USA (date code embossed at right)

In 1982, it then looked like this:
(black border)
SKILSAW® (trade name in red text)
7-1/4” Circular Saw
574 (UL symbol with “Listed 293G” at bottom; this is all to the right of the tool model #)
(red border)
120 Volts AC only 25-60 Hz – 10 Amps
4600 RPM – Type 9
CAUTION: FOR SAFE OPERATION SEE MANUAL. WHEN
SERVICING USE ONLY IDENTICAL REPLACEMENT PARTS.
WARNING: CHECK LOWER BLADE GUARD BEFORE EACH USE.
SUPPORT WORK FIRMLY. USE ONLY RECOMMENDED SIZE
BLADES. WEAR EYE PROTECTION.
DANGER: KEEP HANDS AWAY FROM BLADE.
SKIL CORP. – Chicago, Ill. – Made in USA (date code embossed at right)

For 1983-84, it looked like this:
(black border; tool specifications are moved here)
SKILSAW® (trade name in red text)
7-1/4” Circular Saw
574 (UL symbol/Listed 293G text to the left of tool model #)
120 Volts AC only 25-60 Hz – 10 Amps
4600 RPM – Type 10
SKIL CORP. – Chicago, Ill. – Made in USA
(red border)
CAUTION: FOR SAFE OPERATION SEE MANUAL.
WHEN SERVICING USE ONLY IDENTICAL REPLACEMENT PARTS.
WARNING: CHECK LOWER BLADE GUARD BEFORE EACH USE.
USE ONLY RECOMMENDED SIZE BLADES.
SUPPORT WORK FIRMLY. WEAR EYE PROTECTION.
DANGER: KEEP HANDS AWAY FROM BLADE. (date code embossed at right)

~Ben

View oldnovice's profile

oldnovice

3691 posts in 1995 days


#11 posted 538 days ago

Ben was Skills Inc. Purchased by Bosch and did Skill private label any models for other companies/store brands?

-- "I never met a board I didn't like!"

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BDFan1981

96 posts in 957 days


#12 posted 537 days ago

@oldnovice
Skil was acquired January 3, 1979 by Emerson Electric. In 1992, Robert Bosch acquired a 50% stake in Skil, forming Skil-Bosch (S-B) Power Tool Co. Four years later (in 1996), Robert Bosch acquired Emerson Electric’s 50% share of Skil, and as a result the company was renamed Robert Bosch Tool Co. around 2000.

~Ben

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BDFan1981

96 posts in 957 days


#13 posted 514 days ago

Two generations of the model 537. This is said to be the first Skilsaw to make the transition from 3-wire to 2-wire, circa 1968.

Type 2 (3-wire/all metal housing)

Type 3 (2-wire/double insulated motor)

~Ben

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BDFan1981

96 posts in 957 days


#14 posted 505 days ago

Shoot, that last 537 I mentioned (gray plastic motor housing) is actually a Type 6 unit.

Anyway, here is a Type 10 model 537 saw, with the dark gray plastic housing (obviously circa 1971-1977):

~Ben

View Nicky's profile

Nicky

636 posts in 2719 days


#15 posted 505 days ago

Interesting history. I was not aware of the variants.

Bought my 574 type 10 mid-eighty’s. The saw has been used on every load of rough lumber and every sheet of ply I’ve ever purchased. Built additions, sheds, roofs and many other projects. Still in perfect working order, still looks good.

-- Nicky

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