Cutlery – Cutting tools – Saw
Patent
1989-10-05
1991-05-07
Watts, Douglas D.
Cutlery
Cutting tools
Saw
30124, 30374, B27B 1102, B27B 1909
Patent
active
050125834
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention relates a compass saw comprising a housing connected with a base plate to be placed on a workpiece, a motor driven saw blade, and a suction device located between the housing and the case plate for removal of sawdust and chips. A compass saw comprising a dust suction channel formed in the base plate is already known from DE-OS 25 46 527. However, swiveling of the housing relative to the base plate for executing bevel cuts is not possible with this saw and, moreover, would be impeded by the suction channel. Furthermore, the irregular and bent shape of the suction channel leads to whirling and to a reduction of the suction output. Also, the depositing of sawdust is promoted, which increases the risk of stoppage in the channel.
SUMMARY OF THE INVENTION
The object of the invention is a compass saw capable of executing bevel cuts. The object of the invention is achieved by swiveling the saw housing relative to the base plate. This increases the possibilities of use of the saw while maintaining the channel suction. The suction duct is constructed so as to be completely separate from the carrying stirrup for the motor housing and has no inwardly projecting edges or projections. The effectiveness of suction is accordingly improved decisively, which leads to a complete removal of the saw chips due to the increased suction force. Beyond this, accumulation of sawdust in the suction channel, and accordingly constricting of the channel forming a resistance to flow, is prevented. Should sawdust accumulate nevertheless in unusual cases, e.g. when the sawdust is moist, it can be removed in a very simple manner with a compressed air burst or a water jet. For this purpose, or if the removal of sawdust is not needed, the suction channel can be easily removed from the base plate. The removed suction channel facilitates handling, particularly when sawing with upwardly directed saw blade, since the saw can be grasped by the hand in its center of gravity without the suction channel or the connection pieces interfering (see FIG. 1). The suction channel is advantageously constructed as a light and inexpensive plastic part that can simply and cheaply be produced by injection molding.
Providing countersinking of the fastening screw for fastening the base plate with the suction channel is particularly advantageous because the fastening screw does not project into the duct. A simple handling of the fastening screw is achieved by a slide which promotes flow and which is arranged so as to be displaceable between the base plate and the cover plate and releases an opening for inserting a tool.
The construction of the suction channel with a substantially uniform inner contour without abrupt changes in diameter, reduces the pressure losses in the duct to a minimum. Chips or sawdust which still lie on the tool, are shoveled into the suction channel, so to speak, via a bevel of the channel base at the suction port.
By inclining the suction channel axis relative to the base plate, the suction port is advanced close to the cutting place in the tool, so that the suction channel extends into the workpiece, so to speak, without transition. The other end of the suction channel and the hose connection piece are far enough removed from the support surface of the base plate so as to work without hinderance and so that a suction hose can be mounted.
The recesses or projections which are arranged in the outer contour of the suction channel and correspond to corresponding projections or recesses at the base plate, are also advantageous.
A threaded pin with clamping plate and a helical wheel in the housing base are advantageously used for fastening the base plate, instead of a clamping jaw with screw inserted from the suction channel. Because of the shallow construction of the clamping plate, there is accordingly enough room for a sufficient cross-section of the suction channel. Moreover, the operation of the clamping device is substantially more comfortable, since a tool is no longer required. The helical whe
REFERENCES:
patent: 4090297 (1978-05-01), Wanner et al.
patent: 4665617 (1987-05-01), Maier et al.
patent: 4730397 (1988-03-01), Weiford et al.
Blochle Hans
Stooss Paul
Robert & Bosch GmbH
Striker Michael J.
Watts Douglas D.
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