Building a lathe from industrial scrap

[Music] [Music] in this video I'll show you how I built a metal lathe out of secondhand materials which came from our local scrap yard I live in an area where high-tech equipment is manufactured so you can often find industrial materials like linear guide rails lead screws and gears and lots of scrap metal from which you can build all kinds of stuff the main spindle was a custom made part it is mounted with four tapered roller bearings which sit in rings that are mounted to a front and a back plate that form a housing that is mounted onto the lathe bed then come the pulley the belt and the three horsepower motor that came of an old treadmill the motor is mounted on the top plate of the housing the spindle head matches a Chuck that I also found on the scrapyard it has 130 millimeter diameter and 30 millimeter boring hole the motor control also comes from treadmill which I modified to include a speed control with AHA feedback and a small display to show the RPM the main carriage rides on 20 millimeter linear bearing rails which are 60 centimeters long with for roller bearing blocks a 12 millimeter steel plate is mounted onto the blocks and the carriage is moved by a long lead screw which I can turn via a handle on the rear plate the cross slide writes on 50 millimeter linear bearing rails and four blocks and is also moved via a lead screw the tool post is mounted with a pivot bar on the cross light plate the tailstock is made from thick aluminium that can grip and slide on the 20 millimeter rails the tailstock spindle is actually a 30 millimeter square aluminum bar which is moved by a linear gear and a small gear which can be turned by a handle the spindle slides between two aluminum blocks for higher force a threaded rod can also be used to push the spindle towards the chuck an old drill chuck can hold the drill bit or a live Center I used digital calipers for measuring the carriage cross light and tailstock movement these are handy because they can be zeroed at any position and remember the zero position the whole thing measures around 1 meter by 40 centimeters so it does not take up my whole working bench space it weighs around 85 kilograms and still can be moved to the side of my bench when not in use the lathe bed was made from two arms that came off a scrapped pick-and-place machine of course some cutting and drilling was needed the floor board was made from eighteen millimeter high grade multiplex the arms are bolted together and then bolted on to the floor board here I'm checking the flatness of the base some spaces were needed under one arm to make the bed flat then the arms were bolted tied together lots of metal needed to be cut for this project I mounted an abrasive disc in my circle saw to cut more accurately I used a drill press for drilling holes for tapping thread I first mounted tap in my drill press and turned the Chuck by hand to make the thread start straight then I use a hand tapping tool to complete the thread to accurately drill holes in multiple metal pieces I first glue two pieces together with Gianna blue and then drill the hole through the bottom part using the top hole as a guide after a lot of cutting drilling and tapping I finished the bottom plate front plate side plates top plate the carriage plate cross light plate front plate and tool holder first I mount the bottom plate onto the front and rear plate then the left plate and right plate are mounted it is very important that the front and rear plates are at 90 degrees from the base the bolts construction allows for slight adjustment then the housing is bolted on to the lathe bed here I mount the tapered roller bearing outer rings to the front plate it needs to be very secure so I used 8 bolts the rear bearing rings take less stress so four bolts are sufficient now the main spindle is mounted it needs the front taper roller bearings securing ring and tightening nut then comes the 90 millimeter thread mill pulley which has a key slot then comes the rear taper roller bearing and the pulley belt from the treadmill after the first bearing nut is screwed on the last taper roller bearing can be mounted with the securing ring and the bearing nut to center the bearing outer rings first loosen the bearing ring bolts and then tightened the front bearing nut and then the rear bearing nut you then the bolts of the bearing rings can be tightened the truck is mounted onto the spindle with three bolts note that the spindle main head still needs to be faced now the 20 millimeter linear guide rails can be mounted the horizontal lead screw has Acme thread with four millimeter pitch and two bronze nuts that can be tightened to reduce backlash it is mounted with two bearings to the base rear plate now the carriage plate is mounted onto the linear bearing blocks it is important that the carriage plate is at 90 degrees to the linear rails the carriage can now be bolted to the lead screw nuts the lead screws have right hand thread so I added gear for making the carriage move towards the chuck when turning the handle clockwise the gears came from an old copy machine I get three millimeter carriage movement per turn of the handle now come the 15 millimeter linear bearing rails for the cross light and the front plate of the cross light the cross light leadscrew is the same type as the one controlling the main carriage it is fastened to the front plate with two bearings the bronze leads cronuts are bolted firmly to the cross light top plate the second bronze knot of the leadscrew will help reduce backlash it is pulled to the first nut with four screws which need to be adjusted to get minimal backlash but still allow easy rotation of the lead screw the top plate is then bolted on to the linear bearing blocks the cross light also needs gears for moving the tool holder towards the Chuck when turning the handle clockwise for the cross light I used a higher gear reduction ratio to get around one millimeter cross light movement per turn of the handle the tool holder is made from six metal plates the three top plates are bolted together and the other plates are fixed together with steel pins the tool holder rotates around a 12 millimeter rod which is screwed into the cross light top plate and can be locked by a nut with a handle the cutting tool is secured to the tool holder via three bolts by adding spaces below the cutting tool to cutting head can be adjusted to match the Chuck centerline here you see the motor and speed controller that came from an Old Cutler Marathon treadmill the treadmill also includes an inclination motor and a big control panel for setting speed but these are not needed for the lathe application I reprogrammed the microcontroller to make the system more suitable for the lathe on the primary side the 230 volt AC voltage is rectified to around 320 volt DC which supplies a standard step-down circuit that controls the motor voltage via a pulse width modulation pwm signal that drives the high voltage switch the longer the switch is on the higher the motor voltage and the faster the motor will spin on the secondary side is a microcontroller that generates the PWM signal and sends it to the driver IC via an opto coupler that provides isolation the microcontroller has a speed set input for the manual setting of the motor speed via a potentiometer a disc with holes is mounted on the motor shaft and a light bridge measures the motor shaft speed this signal is also fed to the microcontroller the control loop is very simple first we read Tahoe in and the speed set signal if speed set is higher than Tahoe in we increase the PWM pulse width if speed set is lower than Tahoe in we decrease the PWM pulse width then we return to the beginning the control loop is not fast as it takes time to measure the Tahoe input and I'm using 10 bit PWM resolution but this is not critical because the motor has a big flywheel that will handle most of the low transients as I rotate the motor you can see the Tahoe signal generating pulses I added a small display which will show the motor status the spindle rpm set value and the spindle rpm when the motor is running the slow control loop will also give the motor a soft start due to the slow increase in PWM duty cycle the top plate has four bolts that serve as motor mount after the top plate has been bolted onto the spindle housing the motor can be mounted on top via the nuts the motor height can be adjusted to tension the belt when all is level and the belt is sufficiently tight the nuts can also be tightened I built the control electronics in an aluminium box which is bolted to the side of the spindle housing the motor wires have a connector that plugs into the control box the connector can be reversed to change the rotation direction of the motor it is important to ground the system because the motor is running from primary side and has quite some capacitance to ground after plugging in the mains we can switch on the unit for a test run in stop mode we can dial in the desired rpm and after flipping the switch the motor speed will increase to match the set value you will notice that the inserted steel rod and is wobbling a bit this is because the spindle head has not yet been faced after installing you can see this by using a dial indicator on the spindle face after facing the spindle head the dial indicator now is very steady now we can check the run out of the system after some adjusting of the I get around 0.05 millimeter of run out near the chat which i think is okay when moving the dial indicator across the length of the steel rod we get about the same run-out which is good now I check the side of the steel rod with the dial indicator to check if the carriage runs parallel to the truck centerline when moving the carriage to the end of the rod the dial indicator moves around 0.1 millimeter this can easily be corrected by shifting the carriage linear guide rails slightly after this the carriage now runs perfectly parallel to the Chuck centerline the tailstock is made of thick aluminium plates and bars to cut the aluminum I use a sharp carbide tip blade in my circle saw I spray some wd-40 on the blade and the object before cutting it's a bit scary but it works quite well after a lot of cutting and drilling and tapping here are the parts for the tailstock including the Chuck from an old hand drill I glued a four millimeter rod in the bottom bars that fit the linear guide rail to grip the rails two bolts will clamp the bars to the rail here I'm assembling the bottom section of the tailstock now the front rail guides are added they can be pulled together via two bolts the guide on the rear rail will keep the tailstock steady on the linear guide rails it can move freely but when the two guides are pulled together the tailstock will grip the rails and will not move here I mount the linear gear on the tailstock spindle bar the handle that moves the spindle goes through some bronze bearings and the spindle bar side block the small gear is fixed to the shaft with a steel pin now everything can be mounted on the tailstock top plate the tailstock has a steel back plate with an m12 hole tapped into it an m12 threaded rod can then push the spindle bar from the back for more force after some grazing the whole thing can be assembled the top assembly is then bolted on to the bottom section first I check whether the tailstock spindle moves parallel with the Chuck centerline I adjusted to make it as accurate as possible then I drilled an 8 millimeter hole through the complete spindle bar and drilled a bigger hole for the Chuck shaft the holes will now precisely match the lathe chuck centerline now the Chuck shaft can be pushed into the spindle bar it is a tight fit then the Chuck can be pushed onto the shaft then the spindle can be mounted into the top assembly again and the tailstock is finished the lead screw and linear rails should be kept cleaned from metal chips I therefore built a flexible protection sheet I cut metal strips from a thin metal sheet that was originally a printed circuit board stencil sheet after lining up 20 strips with one millimeter spacing in between I taped them together on top side with heavy duty packing tape and then I also taped the bottom side they can fall together like a harmonica on the lathe I added velcro strips to the spindle housing and on the main carriage I also added velcro on the harmonica sheet to make the harmonica stay in folded shape I heated the sheet a bit now the harmonica sheet can be fixed in place between the spindle housing and the carriage the cross-slide lead screw and linear rails should also be protected so I added a thin protection sheet as well for the other side of the carriage I made a harmonica sheet as well now the lead screw and rails are well protected from metal chips the taper roller bearings must also be protected from metal chips for the front bearing I made a protection cover from six millimeter foam board that can be folded open and fixed around the bearing ring for the rear bearing I made a fixed cover that can be slid on for the bearings inside the housing I also made a cover to measure distance I opened up digital calipers and cut slots in the sides to fix them with screws then I assembled them again for the tailstock caliper and mounted a bracket on the spindle bar then I fixed the caliper with two screws you can now easily check the movement of the tailstock spindle for the cross light it is easy to add a digital caliper as well I also added a plastic protection for the carriage caliper I added a slotted aluminium block to the caliper the block is fixed to the lathe bed side and the caliper head is screwed to the carriage plate it's time for some testing here I use a 20 centimeter long aluminium rod after drilling a center hole the rod end can be secured by the live Center I can fix the tailstock by tightening the top blade bolts to work on the rod end I moved the cutting tool to the other side of the tool holder first a 0 the cross-slide caliper and make a rough cut then I measured a rough cut diameter to get a defined end cut diameter i set the new cross light cut depth to 50% of the difference between the rough cut and the end cut diameter the resulting end diameter is now exactly the target value the service finish is also quite nice let's cut some mild steel bar facing the steel bar works well let's make a 0.25 millimeter cut the surface finish is not as nice as with the aluminium after using a round cutting tool the surface finish is much better let's drill a hole first using the center drill and then using a 10 millimeter drill bit this requires more force so I used a threaded rod to push this tailstock spindle now we can do a parting cut after d sharpening the edges the result looks quite ok finally the lathe can be moved to the side of my working bench building the lathe is a big project and I've learned a lot along the way I probably want to add a compound slide for turning taper I spent about 800 euros on this project and you could buy a small mini lathe for that money but I wanted something small and I wanted a bigger spindle hole and building something yourself is much more fun I hope you enjoyed this video thanks for watching

Channel: Rolandvanroy

Views: 2,891,626

Keywords: DIY lathe, industrial scrap, homemade lathe

Id: Lzytexbrdlg

Length: 21min 53sec (1313 seconds)

Published: Sun May 26 2019