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-Y TABLE Part.2: Building The X-Y Table WITH STEPPER MOTOR CONTROL Last month, we introduced the hardware and software for this XY table with stepper motor control. This month, we cover the construction of the XY table using flat steel sections, threaded rods, the stepper motors and various pulleys. wherever a bolt is called for unless a different type is specified and when we say to drill a hole, it means a 1/4” hole. Whitworth bolts are the only ones readily available from most hardware stores even though Australia is nominally a metric country. Base construction The X-Y table was fabricated from various thicknesses of black steel plate and bar. If you plan to build one we assume you have some experience in cutting, drilling and welding this type of material. Alternatively, you may al-ready have some equipment to which you can fit the motors and driveshafts. We have used 1/4” Whitworth bolts This close-up view shows how the Y-table sits on the X-table, which in turn sits on the base. It also shows the Y-table stepper motor and threaded drive rod. Fig.6 shows the details of the base. Cut two pieces of 25 x 6mm bar 450mm long and mark the centre-line. This centre-line must be extremely accurate as the final result, in terms of smoothness of movement and reproducibility of results, will depend on it. Centre-punch points at the middle (225mm) and 190mm either side of centre and then drill the holes (1/4”). Cut two pieces of 25 x 6mm bar 390mm long. Draw centre-lines on these two bars and drill holes 110mm from each end. The corner pieces are made by cutting four pieces 25 x 25 x 6mm then drilling and tapping each at the centre to take a 1/4” Whitworth bolt. Set up and weld square the four drilled bars, making sure that the corresponding drilled bars are opposite each other, as shown in Fig.6. It is essential that the three-hole bars are parallel to each other. Now weld in the corner pieces. Each one of the these is fitted with a 2” x 1/4” bolt to Mechanical Design & Construction by Ken Ferguson Electronics by Rick Walters 38  Silicon Chip Fig.6: this diagram shows the construction details for the base. It carries the drive motor assembly plus two running rails for the X-table. Note that the diagram is drawn at a scale of 1:4. provide a level-adjustable foot and each has a lock nut, as shown in the end elevation of Fig.6. Next to be made are the drilling support bars. Measure the internal distance between the two 2-hole bars (around 450mm depending on how you welded the base) and cut two pieces of 25 x 6mm flat bar to this length. Weld them each side of centre, spaced 6.35mm clearance (use 1/4” bar + washer). These mount the drill support which will be detailed in a future issue. Table running rails Cut four pieces of 25 x 6mm bar 660mm long. Next cut four pieces of 25 x 6mm bar 100mm long and eight pieces of 25 x 6mm bar 31mm long. Weld these pieces onto two of the 660mm bars at both ends, as shown in Fig.7 and ensure that the slot formed is 1/4” clearance. One of these welded rails becomes the motor mount and table running rail on the base, as shown towards the bottom of Fig.6. JUNE 1999  39 bracket of the lefthand 403mm bar, as shown in Fig.8. Make sure that the top of each running rail is parallel to the top of the associated 403mm bar, then drill both ends. Next, assemble the rails as you did previously for the base, using drilled nuts as spacers. The Y-table is made in exactly the same manner as the X-table, except all dimensions must be such that the wheels for this table must run smooth­ ly along the X-table running rails. The dimensions may vary a millimetre or two depending on the accuracy of your welding. The aim is to ensure that each running rail is parallel to its mate. The details for the Y-table are shown in Fig.9. Fixed clamp assembly This is the drive motor for the X-table. Note the method for attaching the threaded rod. You need a clamp assembly to hold work on the Y-table. This is made as follows. Cut one piece of 12.5 x Parts List Fig.7: details of the motor mount and table running rails (two required). Note the two ¼-inch slots which are used to mount the motor drive and threaded rod assemblies. (Drawing scale 1:3). When finally assembled, this motor mount rail will be positioned at the front. The other welded rail will be part of the X-table. Now drill and mount the running rails to the base using three 1” bolts, washers and nuts and use drilled nuts as spacers between the running rail and the base. The welded running rail goes towards the bottom of Fig.6, as already noted, and the unwelded rail goes towards the top. X-table construction The X-table sits on the base rails while the Y-table sits on the X-table rails. The main details of the X-table are shown in Fig.8. Cut two lengths of 25 x 6mm bar each 395mm long. Scribe a centre-line on each and centre-punch the middle of each bar. Mark points 142mm either side of centre and drill the four holes 40  Silicon Chip (ie, two holes in each bar). Take one 395mm bar and mark 40mm either side of centre and drill two more holes. Cut two 403mm lengths of 25 x 6mm bar. Then scribe a cen­tre-line on each bar and scribe lines 165mm either side of cen­ tre. Then cut six pieces of 25 x 6mm bar 30mm long. Mark the centre-lines on each and drill a hole 15mm from one end. Weld three of these on the top edge of each 403mm bar, centred on the scribe marks. Now weld these two 403mm bars to the 395mm bars, as shown in Fig.8. Take the remaining two 660mm running rails, draw a centre-line on each, punch the centres and drill the holes. Bolt the motor mount rail to the centre mounting bracket of the righthand 403mm bar and bolt the other 660mm rail to the centre mounting X-Y table 2 12V 1.8° stepper motors, (available from Oatley Elec­tronics) 2 4-way terminal strips 4 packs (of 2) 38mm concave wheels, Cowdroy S926 or equivalent 1 length 900mm x 1/2” UNF threaded rod, Blackwoods P/N 00184201 or equivalent 1 phosphor bronze bearing BFB11 (cut in half to make two) 100mm 25mm rod 1.3m 12.5 x 3mm steel bar 1.1m 25 x 3mm steel bar 130mm 50 x 3mm steel bar 12m 25 x 6mm steel bar 1.8m 12.5 x 12.5mm steel bar 2 2½” x 1/4” Whitworth bolts 4 2” x 1/4” Whitworth bolts 6 1½” x 1/4" Whitworth bolts 40 1” x 1/4” Whitworth 52 1/4” Whitworth nuts 80 1/4” Whitworth flat washer 2 2” x 5/16” UNF bolts 2 1/4” Whitworth thumbscrew bolts 8 1/4” Whitworth wing nuts 2 springs to fit over 1/4” Whitworth bolts 8 bolts, nuts and washers to suit stepper motors Fig.8: this diagram shows the main details of the X-table. It sits on the base and carries the two running rails for the Y-table, plus the Y-table drive motor assembly. (Drawing scale 1:4). 12.5mm bar approx­imately 415mm long (enough to reach the outside edges of the Y-table frame). Draw a centre-line and centre-punch the middle. Mark 130mm either side of centre then drill and tap the three holes (1/4” Whitworth). Cut two pieces of 25 x 3mm bar 380mm long. Scribe a centre-line and centre-punch. Mark 130mm either side of centre and drill three clearance holes. Take one length of 415mm bar, face it running away from you and weld a piece of 12.5 x 3mm bar 15mm long to the front righthand side JUNE 1999  41 Fig.9: the Y-table carries a moveable clamp assembly, to secure the job. (Drawing scale 1:4). ensuring that there is no weld on the inside. This becomes the corner stop. Now bolt the 380mm bar to the bottom of the 415mm long 12.5 x 12.5mm bar, using three 1½” bolts. This is the job support assembly. Cut six pieces of bar 12.5 x 3mm 15mm long, then scribe the centre-line and a point 7mm from one end on each. Centre-punch and drill a 1/4” clearance hole in all six pieces. Place one of these pieces on each of the three bolts on the 415mm bar and secure them with nuts. Cut two pieces of 12.5 x 3mm plate 360mm long and weld one to the three plates 5mm away from the corner stop. This assembly becomes the fixed clamp which is welded parallel to the wheels, with its outside edge 42  Silicon Chip 32mm from the outer edge of the Y-table frame. Remove the nuts from the three bolts and fit a washer and wing nut to each. Moveable clamp assembly Cut three lengths of 12.5 x 12.5mm bar 445mm long. Take one bar and as a first step, using the pieces already cut and drilled, make a mirror image of the fixed clamp assembly (just described) but without the corner stop piece. Now pull it apart and draw a centre-line on its face at rightangles to the top. Centre-punch 90mm either side of centre and drill and tap each hole (1/4” Whitworth), then reassemble. The other two 445mm bars should have holes marked 6mm from each end. Drill one bar at both ends and insert a 2½” bolt in each end and weld the heads to prevent them turning. Drill the third bar with 1/4” clearance holes and scribe a centre-line on the face at rightangles to the top. Drill 1/4” clearance holes 90mm either side of centre, then drill and tap (1/4” Whitworth) holes 140mm each side of centre. Now fit the load springs onto the bolts and screw them into the moveable clamp bar. Then fit the two 1/4” x 1” Whitworth thumb-screws for the fine adjustment. Drive brackets The next step is to make two drive brackets, one for the X-table and one for the Y-table. The details are shown This photo shows the fully assembled X-Y table, with a blank piece of PC board mounted in its clamps. in Fig.10. Cut two lengths of 25 x 3mm bar 110mm long and mark the centre-lines. Mark 40mm either side of the centre-line and drill the holes. Cut two pieces of 25 x 3mm bar 60mm long, scribe a centre-line and centre-punch 9mm and 13mm from one end. Drill 5/16” holes and file them out to a slot. The slotted pieces are then welded to the centre-line of each 110mm bar. Fig.10: the drive bracket details. Two are required, one for the X-table and one for the Y-table. (Drawing scale 1:3). Motor mounting brackets These are shown in Fig.11. Cut two lengths of 50 x 3mm bar 60mm long, then mark and drill a hole 10mm from each end. Cut four pieces of 12.5 x 3mm bar 63mm long and two pieces 32mm long. Weld two sets of three plates, as shown and then grind off the excess weld. Weld each of these to the 60mm plates. Then fit and tack weld the two 1” bolts as shown. Motor mounting plates Cut two plates 62 x 62 x 3mm (or JUNE 1999  43 Fig.11: here’s how to make the motor mounting brackets. Two are required, one for each stepper motor. (Drawing scale 1:3). Fig.12: details of the motor mounting plate. The motor mounts as shown at right. This assembly is then bolted to the motor mounting bracket which in turn is bolted to the drive rail. (Drawing scale 1:3). size to suit your motors) and drill the four motor mounting holes in each. Drill two holes 10mm in from two edges, then fit two 1” bolts and tack weld the heads. Now mount the motors, using two nuts as adjusters as detailed in Fig.12. Fabricate and fit a terminal block bracket if you wish. Bearing brackets One of these is mounted on each motor running rail, at the opposite end to the motor, to support the threaded rod. Cut two lengths of 25 x 3mm bar 60mm long for the mounting plates of the bearing brackets. Drill each one 10mm from one end. Cut two 50mm lengths of 12.5 x 25mm bar and drill a 1/2” hole 12mm from one end in each. Fit a phosphor-bronze bearing in each. Drill an oil hole, which will now make this side the top of the bearing bracket. Weld one side of each bearing holder to a moun­ting plate. Note: only 44  Silicon Chip one side is welded to allow squaring up later if the two are not exactly at rightangles. was cut with a hacksaw, to allow the rod to push on over the pin. Threaded rod drive nut If you have tested and adjusted each table to run smoothly as you built it, the next stage is to align the motors so that the threaded drive rods are parallel to the frames, for both the X and Y axes. Don’t forget to fit the drive nut onto the threaded rods before you make these adjustments. Now insert the drive nut bolts into the drive brackets and tighten the nuts with your fingers. You can now turn the rods by hand along the full traverse length, checking for smooth operation of the X and Y tables. Make any adjustments then nip the nuts tight with a spanner. In the next article, we will describe how to wire the motors and power supply to the stepper motor cards and detail the Z-axis support. This support will carry a drill, plotter pen SC or whatever. The drive nuts are driven by the threaded rod and one moves each table. We tried to use UNF nuts on the rod but they were not successful. Cut two 40mm lengths of 25mm rod and face, drill and tap each one 1/2” UNF in a lathe. This done, weld a 2” x 5/16” UNF bolt to the centre of each drive nut. We cut the 900mm threaded rod in half but if you want greater X-Y movement you will need to use two rods. For each rod, lathe face one end and turn down 13mm to 3/8” (to suit the bear­ing). Face and drill the other ends to suit your motor shafts. The motors we used each had a pin through the shaft and we recom­mend that you use this type of motor as it simplifies the mechan­ical connection of the motor shaft to the rod. A slot Final assembly