A couple occasions now I’ve attempted to make an adapter to Mount to the D shaft of a stepper motor. Last week I tried to adapt a 8mm D shaft to a 1/2-20 drill Chuck. 1/2-20 all thread cut to length and drilled to 8mm. Added a 6-32 set screw at the end of that to clamp on the flat. Was very catywampous. Added another to contact the other end of the shaft. Much better now but still more runout than I would like. Not a big deal on that particular project, it’s just for spinning a quarts glass tube in a flame to seal it. But short of getting a D broach how does one connect to a d shaft accurately?
D shaft adapter?
- Thread starter no704
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RoninB4
Well-known member
-You could expand upon your first attempt. Careful dimensioning of the shaft, make a slip fit blind bore in an adaptor so it locates well on the remainder of the shaft diameter. Use a small piece of key-stock to fit between the shaft flat and the bore, profile/fitment as your ambition dictates. Two small set screws to bear on the key-stock should be enough. You'll want the adaptor to be large enough in diameter so the wall thickness has an adequate number of threads (1 to 1-1/2 X D of set screw) for the set screws. Cup point, dog point, or shop altered set screws are advised to reduce thread end deformation. The diameter of the adaptor end will likely be too large to fit the average drill chuck so turn the other end down to fit the chuck. Aluminum can be used to keep the rotating mass lower, the 7000 series has superior mechanical properties but 6061 is more commonly available. Using steel allows other options.
-Or you can ignore the above and order the broach. Post what you do for future reference.
mike93lx
ALLIANCE MEMBER
Is this for work?
If so, you should show that the broach is the fastest, easiest and cheapest way, then spend a month trying all kinds of other options first
If so, you should show that the broach is the fastest, easiest and cheapest way, then spend a month trying all kinds of other options first
Has not been a super huge issue with this application. RPM is super slow like maybe 20. And using the cheapest Chuck I could find 5/8” Chuck for $28 on amazon. Maybe actually ream the hole and a roll pin axily! The motor shaft seem pretty well made. Did a smaller version with the same poor results.
LopezBart
Well-known member
A drilled hole won't do; it needs to be reamed, and the threads should be cut concentric w/ the hole.... chucking a piece of 5/8" drill rod in a collet and leaving enough sticking out for threading, drill and ream 8MM through. Turn down the end and cut your thread for the drill chuck. Now the 8 mm hole and thread are on the same axis. Remove from lathe and add a set screw to rest in the D flat.
whateg01
Well-known member
A drilled and bored hole would be fine. I don't know how much catty wampas is allowed but even a drilled hole could be fine as long as it's done right. Was this drilled in a vise or on a lathe?
This one I drilled on the lathe with a 5c collet. But I have been known to keep a small 3jaw Chuck on my Bridgeport and have had better luck with that sometimes.
LopezBart
Well-known member
You can make a D bit reamer that will work like a charm from a piece of drill rod.....
OccupantRJ
Well-known member
Without a reamer you should be able to get a bit better bore result by center drilling, then a pilot hole, then stepping up in moderate increments, drilling slowly, and taking only a few thousandths with the last drill size. In case you are not aware if you end up buying a reamer that they are available on size, undersize, and oversize by a prescribed amount for slip fit and press fits. If you let the reamer push against the bottom of the hole it will likely go oversize. Use plenty of oil and slower rpm with the reamer. I like spiral fluted chucking reamers. You can turn the threaded end diameter while set up for drilling to help maintain some concentricity. Another method is to press the chuck apart. Machine a threaded end on your adapter to fit the chuck. Attach chuck to it. Have the chuck bottom on a shoulder, not the adapter bottom into the chuck threaded hole. Insert the chuck body into a collet if you have that size and then do the rest of your machining. If it is a larger chuck body it can be indicated to run true In a lathe chuck. There are several methods to get different results. I had to deal with small chuck adapters at work and sometimes you have to get creative.