About the stub drills: How are you holding them? I am having trouble finding anything with a 1/4" shank.
I am also having trouble finding a collet reducer set with 3/16 and 1/8 inner diameter.
For 1/8" tooling, I use these adaptors, they work great. They are 1/4" to 1/8" adaptors, though, so not 1/2" outer diameter.
In this case, Iāve found that using a #3 center drill works pretty well instead of a stub drill. Either works, but the #3 is a 1/4" shank, so no adaptors needed.
In the assembly directions, there is a sentence about the linear rails and lead screw. āBoth should be about 250mm longā. But, the BOM asks for a 300mm set. This is not hard to adjust for, but it is inconsitent.
At the time, I couldnāt find a 250mm kit that shipped within the US. That may have changed in the interim, so if you find a part, let me know. I can add it into the BOM.
Actually, I bought the 300 a long long time ago. I havenāt cut my z-stage yet, still getting materials. If I need to I will just build a 300 mm design. Like I said, no big deal. I was just unclear what the current state is, 250 per the instructions or 300 per the BOM.
It should be fine. I believe that is what mine is. The only issue I am having is that I need to bring my top bar forward (add another 2x4) because I had to move the attachment points to the top of the ring system. I suspect you will be required to do that whether you use the 250mm or the 300mm kit.
There is enough room on either end of the linear guides for the extra length, if you donāt have the tools to cut down the shafts. With the ring system, you should be able to have all the excess extend towards the sled itself. If you have a linkage, like me, then the only place for it to go is up.
Keep in mind that these shafts are surface hardened, so you need to use an abrasive cutting disk to shorten them. Angle grinder/dremel tools work fine.
Also, to add onto what @ShadyG was saying, the higher center of gravity of the new sled means that the top beam needs to sit higher in the machine Z direction. On my setup, I needed about 4" from the top of the spoilboard to the plane the chains exist in.
For all the holes, Iāve used a #3 center drill to drill a pilot out for the final hole. This reduces the number of tool changes needed to complete the job. The nice thing about the #3 is that the shank diameter is 1/4", so it fits in the router without needing an adaptor. I used my drill press to drill everything out to itās required diameter, but you could easily use a hand drill and just keep it perpendicular.
Sometimes the collets are just wrong, too tight, too loose. If you canāt fit a standard size bit into the collet (and you havenāt already permanently modified your router) Iād recommend taking it back for a replacement.
Whenever I buy a router now I specifically test the collet holds bits correctly.
The G-code specifies for T4 (the drill) to go to a depth of 3mm (1/8"), so it wonāt need any changes. I assumed when I was programming this that the user would be using a stock Maslow to make the components, so I didnāt want to use any big Z moves to save on run time.