Downham, Elliot, Gate, Linley, mini Jig borer CNC conversion
|Bob McDougall||22/08/2019 22:44:11|
|39 forum posts|
Just added the Z axis mechanics to my Lovely Downham mini Jig borer. all the pics for the Z axis manual removal are in my album. I didn't record the X and Y conversions as they were relativley straight forward. The dismanteling may be of interest .
Was all going well until I got stuck with , how the hell does this bit come apart. Oh thats not a hole its a slotted spring pin. I'll post some pics of the X and Y tomorrow. Hopefully the pics are self explanatory. The new Z uses 12mm ballscrews each side of the spindle, NEMA17 x 40mm, 2A. The fixed end is made from two 10x28x8 deep groove bearings with a 0.2mm spacer between the outer rim so when the ballscrew is tightened it pulls the middles together to reduce backlash. they are sunk 10mm into the 12mm aluminium plates. Used solid 5-8mm coupling on the motor and the thin 3mm threaded bar can give for misalignment. I might put a shroud around them as they are vunerable. Had to unscrew both ballnuts fully off the screws for installation. sleves to hold the balls in but still lost one ball. 9.6mm OD 8mm ID sleve.
Edited By Bob McDougall on 22/08/2019 22:45:37
|Bob McDougall||24/08/2019 22:33:44|
|39 forum posts|
A frequent question is " how big steppers do I need". Well I need bigger ones. Quick test with GRBL Plotter. These moved a bit but it was clear they became out of sync and stopped altogether often. Current ones are Nema17 42mm body 0.45Nm .So I've ordered Nema23 56mm long 2.8A 1.26Nm . I could have added a gear reduction and used the origional ones but I want Z speed for nameplate and 3D map cuts and the pinions and pulleys would have been almost as much as the motors, £30 a pair for the 23 size. Will need to take it all apart and re-work. I hate having to take the ballnuts off the ballscrews but Im getting better at it.
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