Hi
It was too much to upload in one go (exceded 2000 characters) so heres the rest.
This bolts on with the post to form the counter balance spring lower mounting. The pivot for the swinging arm I turned from a piece of brass hex but a nut and bolt with a shank would do. Drill a 10mm hole at the top of the post to accommodate the pivot. The position of the pivot is such that the swinging arm is parallel to the channel at the bottom of its cut. Drill a hole for the on off switch and two 5mm holes tapped out 6mm for mounting the micro switch bracket. The micro switch bracket is made from a strip of steel 135mm X 25mm x 2mm, sturdy enough to hold the switch but thin enough to be bent into place when setting the switch. When the saw finishes cutting through the work piece it will drop slightly before switching off the power then come to rest on a stop. The stop will in fact have three functions. Firstly a stop, obviously, secondly it can be used as a depth of cut limiter and thirdly as a prop to keep the saw out of the way while setting up the work piece in the vice. Cut a piece of 30mm x 4mm to 145mm in length to make the stop mounting post. Drill two 2mm holes at one end and clamp in position on the channel checking with a square. Drill through the channel with the 2mm drill then open out the holes in the channel and the post to 6mm. Drill a 1\4 inch hole at the top. Cut a block of steel x25mm x x25mm x x22mm and drill through to 5mm and tap out 1\4 inch whitworth. (The thumb screw I found is 1\4 whit) Cross drill the block to 6mm. A 6mm length of steel bar bent over at one end forms the adjustable stop. Bolt the stop post to the channel with two 6mm nuts and bolts. The block is bolted to the top of the post with a 1\2 inch long 1\4 whit bolt, the 6mm steel bar drops through the hole and is held in position with the thumb screw. The bar length is designed so that when it is allowed to drop to the bottom it is in the correct position for the saw to rest when the power is cut. Last but not least we will need a vice to securely hold the work piece during the cutting operation. The two vice jaws are made out 40mm x 40mm x 6mm angle iron cut to 95mm in length. Now you would think that angle iron would be 90 degrees wouldnt you but the bit I was using wasnt as is clearly demonstrated in the photos. Although this is going to be a fairly crude vice it will work a lot better if the jaws close together reasonably well. To get over this I clamped the two jaws back to back in the milling machine vice and took light cuts until the two faces were reasonably flat. The same could be achieved in the bench vice with a flat file and a square. The fixed jaw of the vice simply bolts onto the channel with two 10mm bolts, making sure it is as square as possible. Two brackets 26mm high x 22mm x 25 wide with 10mm holes in are bolted on using the same jaw mounting bolts. (These brackets were an after thought; there use will be demonstrated later). I wrestled for some time about how to make the movable jaw and eventually settled on the method here. After all this does not need to be a precision machine vice but simply good enough to hold the work secure and reasonably square while the saw does its work. Two slots need to be cut in the channel 8mm wide x 110mm long with centres 53mm apart. I did this by drilling a series of holes using the bench pillar drill to remove much of the waste and then milling out on the milling machine. Alternatively use flat and round files to complete the slots. The movable jaw now has two 6.8mm holes drilled at the same centres as the slots and then tapped out to 8mm. Acquire or make two 8mm studs to the dimensions shown. Cut a piece of 40mm x 10mm x 85mm steel and drill two 8mm holes on the same centres as the stud holes and slots. This piece fits inside the channel and helps to guide the movable jaw. A 300mm length of 12mm threaded rod is used for the vice screw. The screw block is made from a piece of 25mm x 25mm x 65mm long. Drill and tap 12mm to take the vice screw and then drill the two 8mm mounting holes. Clamp the screw block in place on the channel checking for square and drill through with the 8 mm drill. A 1.5mm thick x 32mm x 45mm `U` Shaped piece of brass with a 6mm thick x 45mm x 10mm aluminium spacer is fixed to the rear vertical face of the movable jaw with two 6mm bolts screwed into threads tapped into the vertical face. Two small brass studs are also fixed to the vertical face of the movable jaw with 6mm countersunk machine screws (their use will be demonstrated later). File off any protruding threads to leave the vice jaw smooth. The end of the vice screw is fitted with a turned and internally threaded brass boss with a groove in it held in place with 1\8 inch steel roll pin. The movable vice jaw is simply pushed forward by the brass boss pushing on the rear vertical face of the jaw and pulled back by the action of the groove in the boss which is located in the `U` shaped slot in the brass plate. An alternative to a turned brass boss could be to fit two nuts with a 1.5mm space between them and then drill and pin the nuts in place, file the nuts round and make the slot in the `U` shaped piece of brass to suit. Once all the parts are fitted to the movable jaw all protruding screw threads and heads must be filed flush. I found a hand wheel in the scrap box that I used on the vice screw held in place with a grub screw. As an alternative cross drill the end of the screw and fit a short length of bar. The vice does not need to exert any great pressure, just enough to hold the work piece. Two lengths of 1\2 inch x 1\2 inch aluminium angle are pop riveted to the sides of the channel to allow the saw to be fixed on to a 140mm x 30mm x 535mm piece of wood, this makes it easy to clamp to the bench or fit into a workmate type bench. I think that just about covers everything on the mechanical side. Steel has a nasty habit of corroding so with the dregs of a few tins of hamerite I painted it up a little. Dont paint where the saw slides on its swinging arm or where the movable vice jaw runs though. Connecting the power supply to the saw is via two brass rods mounted on a hard wood base. The hardwood insulates the power from the metal of the machine. To make the power supply connector first cut a piece of hardwood to 120mm X 30mm X 15mm thick. Cut two pieces of 3.2 mm thick brass 38mm X 25mm. Drill a 6mm hole dead centre of each piece and then drill and countersink two screw holes in each piece. The brass rods I made in the lathe by cutting off a 50mm length of 9/16 diameter and turning the first 10mm down to 6mm and threading with a 6mm die. Alternatively drill into the end with a 5mm drill and then tap out to 6mm. Mount the rods on their respective brass plates with a 6mm nut or bolt. Mark out the hardwood block and recess where the nuts will be with a 12mm drill to a depth of 10mm. Drill two 6mm holes for mounting the block on the saw frame. Hold the brass plates on the hardwood block and mark the screw holes. If you use brass screws like I did its best to pre drill the screw holes with a 2mm drill to avoid the screws snapping off. Hold the hardwood block on the saw base and mark through the mounting holes. Drill out to 5mm and tap out to 6mm. Although the base is only 3.3mm thick it will take enough thread to hold the block securely enough. Screw the hardwood block to the base with a couple of pan head machine screws. Screw the brass plates and rods onto the hardwood block with one brass screw in each. Anything with crocodile clips, e.g. the battery charger, jump leads off a battery or even an adapter made up that plugs into the car cigarette lighter socket can now be quickly connected to the machine. The electrical side of things is dead easy. All you need is to find the two wires on the motor that give the fastest speed. One will be common earth; the others will be for the different speeds. Cut the unwanted wires out of the plug. Use crimp type electrical connectors throughout to make good connections. Take one wire from the motor to the brass rod and connect with a brass screw in the unused screw hole. The other wire from the motor goes to the fuse holder. (I used a 10 amp fuse, the same as the fuse rating on the car the motor came from). From the fuse holder to the on/off switch, from the on/off switch to the micro switch and finally from the micro switch to the brass rod making the connection with a brass screw into the last unused screw hole. The switches and fuse holder can be obtained from Maplins or car accessory shops. Incidentally if you reverse the + and wires on the power supply it just makes the motor run in the opposite direction. I have run the motor in both directions and fitted the blade in both directions and as far as I can see it makes no difference what so ever to the performance of the saw. In operation the saw runs reasonably quietly. Its not the fastest thing in the world but sipping tea while a machine does the work for me is a lot better than doing it by hand and Bens a lot happier as well. There is a fair bit of hard work in making this tool but once made cutting metal becomes a pleasure and not a chore. It will of course cut any material that a hacksaw is normally capable of cutting so it is not restricted to metal only.
A FEW AFTER THOUGHTS
The brass pivot that the swinging arm mounts on could do with being bigger. There is some play there which becomes greater at the far end. I had to experiment with large plastic and brass washers too get rid of as much play as possible. It was while clearing up that I noticed the wiper arm spindle is ground and hardened and runs in two bronze bushes in an aluminium housing, this I am sure could be easily adapted to make the swinging arm pivot.
The counter balance spring was a modification as there was too much forward pressure on the saw blade. The photos show experiments with mole grips and lead weights until an ideal balance was found. It was then just a case of finding a spring with the right pull to make the counter balance. This is not an exact science but more a case of playing about until it felt and sounded right. Perhaps if the motor was fitted to the rear of the swinging arm pivot thus forcing the arm to naturally tip backwards would be a better idea. Different weights could then be added to the front of the swinging arm to give the best cut.
The reason for the brackets and studs on the vice jaws is to help hold down larger round tube sections by the use of plastic pull straps. See the photos for an example. Im sure there is a better way but I havent thought of one yet.
An easier way to make the power supply connecting rods would be to use copper pipe (central heating pipe, ½ inch). Flatten one end for about 30mm and bend over at 90 degrees. Drill a couple of holes and screw onto a piece of wood. Make the electrical connection to one of the screws or solder directly onto the copper pipe.
chers
Rich
It was too much to upload in one go (exceded 2000 characters) so heres the rest.
This bolts on with the post to form the counter balance spring lower mounting. The pivot for the swinging arm I turned from a piece of brass hex but a nut and bolt with a shank would do. Drill a 10mm hole at the top of the post to accommodate the pivot. The position of the pivot is such that the swinging arm is parallel to the channel at the bottom of its cut. Drill a hole for the on off switch and two 5mm holes tapped out 6mm for mounting the micro switch bracket. The micro switch bracket is made from a strip of steel 135mm X 25mm x 2mm, sturdy enough to hold the switch but thin enough to be bent into place when setting the switch. When the saw finishes cutting through the work piece it will drop slightly before switching off the power then come to rest on a stop. The stop will in fact have three functions. Firstly a stop, obviously, secondly it can be used as a depth of cut limiter and thirdly as a prop to keep the saw out of the way while setting up the work piece in the vice. Cut a piece of 30mm x 4mm to 145mm in length to make the stop mounting post. Drill two 2mm holes at one end and clamp in position on the channel checking with a square. Drill through the channel with the 2mm drill then open out the holes in the channel and the post to 6mm. Drill a 1\4 inch hole at the top. Cut a block of steel x25mm x x25mm x x22mm and drill through to 5mm and tap out 1\4 inch whitworth. (The thumb screw I found is 1\4 whit) Cross drill the block to 6mm. A 6mm length of steel bar bent over at one end forms the adjustable stop. Bolt the stop post to the channel with two 6mm nuts and bolts. The block is bolted to the top of the post with a 1\2 inch long 1\4 whit bolt, the 6mm steel bar drops through the hole and is held in position with the thumb screw. The bar length is designed so that when it is allowed to drop to the bottom it is in the correct position for the saw to rest when the power is cut. Last but not least we will need a vice to securely hold the work piece during the cutting operation. The two vice jaws are made out 40mm x 40mm x 6mm angle iron cut to 95mm in length. Now you would think that angle iron would be 90 degrees wouldnt you but the bit I was using wasnt as is clearly demonstrated in the photos. Although this is going to be a fairly crude vice it will work a lot better if the jaws close together reasonably well. To get over this I clamped the two jaws back to back in the milling machine vice and took light cuts until the two faces were reasonably flat. The same could be achieved in the bench vice with a flat file and a square. The fixed jaw of the vice simply bolts onto the channel with two 10mm bolts, making sure it is as square as possible. Two brackets 26mm high x 22mm x 25 wide with 10mm holes in are bolted on using the same jaw mounting bolts. (These brackets were an after thought; there use will be demonstrated later). I wrestled for some time about how to make the movable jaw and eventually settled on the method here. After all this does not need to be a precision machine vice but simply good enough to hold the work secure and reasonably square while the saw does its work. Two slots need to be cut in the channel 8mm wide x 110mm long with centres 53mm apart. I did this by drilling a series of holes using the bench pillar drill to remove much of the waste and then milling out on the milling machine. Alternatively use flat and round files to complete the slots. The movable jaw now has two 6.8mm holes drilled at the same centres as the slots and then tapped out to 8mm. Acquire or make two 8mm studs to the dimensions shown. Cut a piece of 40mm x 10mm x 85mm steel and drill two 8mm holes on the same centres as the stud holes and slots. This piece fits inside the channel and helps to guide the movable jaw. A 300mm length of 12mm threaded rod is used for the vice screw. The screw block is made from a piece of 25mm x 25mm x 65mm long. Drill and tap 12mm to take the vice screw and then drill the two 8mm mounting holes. Clamp the screw block in place on the channel checking for square and drill through with the 8 mm drill. A 1.5mm thick x 32mm x 45mm `U` Shaped piece of brass with a 6mm thick x 45mm x 10mm aluminium spacer is fixed to the rear vertical face of the movable jaw with two 6mm bolts screwed into threads tapped into the vertical face. Two small brass studs are also fixed to the vertical face of the movable jaw with 6mm countersunk machine screws (their use will be demonstrated later). File off any protruding threads to leave the vice jaw smooth. The end of the vice screw is fitted with a turned and internally threaded brass boss with a groove in it held in place with 1\8 inch steel roll pin. The movable vice jaw is simply pushed forward by the brass boss pushing on the rear vertical face of the jaw and pulled back by the action of the groove in the boss which is located in the `U` shaped slot in the brass plate. An alternative to a turned brass boss could be to fit two nuts with a 1.5mm space between them and then drill and pin the nuts in place, file the nuts round and make the slot in the `U` shaped piece of brass to suit. Once all the parts are fitted to the movable jaw all protruding screw threads and heads must be filed flush. I found a hand wheel in the scrap box that I used on the vice screw held in place with a grub screw. As an alternative cross drill the end of the screw and fit a short length of bar. The vice does not need to exert any great pressure, just enough to hold the work piece. Two lengths of 1\2 inch x 1\2 inch aluminium angle are pop riveted to the sides of the channel to allow the saw to be fixed on to a 140mm x 30mm x 535mm piece of wood, this makes it easy to clamp to the bench or fit into a workmate type bench. I think that just about covers everything on the mechanical side. Steel has a nasty habit of corroding so with the dregs of a few tins of hamerite I painted it up a little. Dont paint where the saw slides on its swinging arm or where the movable vice jaw runs though. Connecting the power supply to the saw is via two brass rods mounted on a hard wood base. The hardwood insulates the power from the metal of the machine. To make the power supply connector first cut a piece of hardwood to 120mm X 30mm X 15mm thick. Cut two pieces of 3.2 mm thick brass 38mm X 25mm. Drill a 6mm hole dead centre of each piece and then drill and countersink two screw holes in each piece. The brass rods I made in the lathe by cutting off a 50mm length of 9/16 diameter and turning the first 10mm down to 6mm and threading with a 6mm die. Alternatively drill into the end with a 5mm drill and then tap out to 6mm. Mount the rods on their respective brass plates with a 6mm nut or bolt. Mark out the hardwood block and recess where the nuts will be with a 12mm drill to a depth of 10mm. Drill two 6mm holes for mounting the block on the saw frame. Hold the brass plates on the hardwood block and mark the screw holes. If you use brass screws like I did its best to pre drill the screw holes with a 2mm drill to avoid the screws snapping off. Hold the hardwood block on the saw base and mark through the mounting holes. Drill out to 5mm and tap out to 6mm. Although the base is only 3.3mm thick it will take enough thread to hold the block securely enough. Screw the hardwood block to the base with a couple of pan head machine screws. Screw the brass plates and rods onto the hardwood block with one brass screw in each. Anything with crocodile clips, e.g. the battery charger, jump leads off a battery or even an adapter made up that plugs into the car cigarette lighter socket can now be quickly connected to the machine. The electrical side of things is dead easy. All you need is to find the two wires on the motor that give the fastest speed. One will be common earth; the others will be for the different speeds. Cut the unwanted wires out of the plug. Use crimp type electrical connectors throughout to make good connections. Take one wire from the motor to the brass rod and connect with a brass screw in the unused screw hole. The other wire from the motor goes to the fuse holder. (I used a 10 amp fuse, the same as the fuse rating on the car the motor came from). From the fuse holder to the on/off switch, from the on/off switch to the micro switch and finally from the micro switch to the brass rod making the connection with a brass screw into the last unused screw hole. The switches and fuse holder can be obtained from Maplins or car accessory shops. Incidentally if you reverse the + and wires on the power supply it just makes the motor run in the opposite direction. I have run the motor in both directions and fitted the blade in both directions and as far as I can see it makes no difference what so ever to the performance of the saw. In operation the saw runs reasonably quietly. Its not the fastest thing in the world but sipping tea while a machine does the work for me is a lot better than doing it by hand and Bens a lot happier as well. There is a fair bit of hard work in making this tool but once made cutting metal becomes a pleasure and not a chore. It will of course cut any material that a hacksaw is normally capable of cutting so it is not restricted to metal only.
A FEW AFTER THOUGHTS
The brass pivot that the swinging arm mounts on could do with being bigger. There is some play there which becomes greater at the far end. I had to experiment with large plastic and brass washers too get rid of as much play as possible. It was while clearing up that I noticed the wiper arm spindle is ground and hardened and runs in two bronze bushes in an aluminium housing, this I am sure could be easily adapted to make the swinging arm pivot.
The counter balance spring was a modification as there was too much forward pressure on the saw blade. The photos show experiments with mole grips and lead weights until an ideal balance was found. It was then just a case of finding a spring with the right pull to make the counter balance. This is not an exact science but more a case of playing about until it felt and sounded right. Perhaps if the motor was fitted to the rear of the swinging arm pivot thus forcing the arm to naturally tip backwards would be a better idea. Different weights could then be added to the front of the swinging arm to give the best cut.
The reason for the brackets and studs on the vice jaws is to help hold down larger round tube sections by the use of plastic pull straps. See the photos for an example. Im sure there is a better way but I havent thought of one yet.
An easier way to make the power supply connecting rods would be to use copper pipe (central heating pipe, ½ inch). Flatten one end for about 30mm and bend over at 90 degrees. Drill a couple of holes and screw onto a piece of wood. Make the electrical connection to one of the screws or solder directly onto the copper pipe.
chers
Rich
