Notes about tapping
Tapping means to cut threads on the inside of a hole. There is an entire industry based around this process, and some people take it very seriously. If you look around the internet you can find 1,000s of site with "drill and tap" charts. These charts tell a person how big of a hole is required to be tapped to a certain thread size. There is a great write-up over at Wikipedia describing Tap and Die.
For instance, if you want to have a finished, threaded hole that will accept a standard M5 bolt (.8 pitch), you'll actually need to start with a hole that is only 4mm. This is because as you're cutting the threads into the hole, you'll obviously need material to remove.
Some people use a t-handle (which is my preference) something like this from amazon works well. You would also need a tap like this. Other people just put the tap into a hand drill and set the torque to a low setting (something like 10 on a scale 1-21, where 21 is "drill"). Because makerslide is made from aluminium, which is a "soft" metal, it's fairly easy to tap. But, you'll need a cutting fluid to make it easier. And others just grab onto the end of the tap with a pair of vise grips or other pliers. This is obviously not the recommended way, but can get you by in a pinch.
When tapping, it's important to not just torque down and twist as hard as you can. Remember, as you're cutting the threads into the hole, the tap is removing materal. That material has to go someplace. Ideally, the tap will be trying push the material out of the way either by bringing it back up the hole, or pushing it out the bottom. (If you're doing a through hole you can watch the material start coming out the back of the hole.) But if you encounter resistance, it's probably due to chip buildup along the tap. Slowly reverse the tap until it's out of the hole, clear the chips from the tap, and start again. Depending on how deep the hole is you're tapping, it may take several times of cutting/removing to accomplish your depth.
Alternative to tapping an extrusion
A great alternative to tapping is the use of tapping joints like this. They are self-tapping and require a TORX driver but the advantage is that you don't have to tap anything and their heads slide into the T-slot of a perpendicular extrusion. If a hole is drilled in that perpendicular extrusion, that hole can be used to allow the TORX driver access to the trapped tapping joint so that it can be tightened.
Identify and Organize
- Identify and organize all of the parts: (overhead picture of layout)
Wheel Sets and Smooth Idlers
- Assemble Wheel Sets and idlers (16 wheels + 4 idlers) (video)
- Tap one piece of 375mm makerslide, 4 holes total (2 on each end)
- Assemble the Gantry (X-axis)(video), snug up bolts, don't use locktight
- Put wheels on Y axis Plates
- Tap 2 pieces of 375mm makerslide, 8 holes total, 2 holes on each end x 4 ends.
- Make sure bottom wheels (eccentric wheels) are loose on y axis plates, slide makerslide onto v-wheels (it'll be a little sloppy, that's OK)
- Bolt End plates to makerslide. 4 bolts total. Just snug end plates, not super tight
- Square end plates (insert video)
The assembly that represents the X axis is a dual purpose part. On the back side (10ga steel plate), the motor, idlers and pulleys are mounted. When combined with the belt, these items give motion to the X (left <-> right when looking from the front of the machine) axis. On the front side of the plate is an aluminum multipurpose plate from buildlog.net.
'When mounting the motor to the back plate:'
- run the bolts from the inside through the holes, and use the nuts on the motor side. Its backwards from what you might think is standard, but gives us more clearance for the idlers and belt.
- use 3 extra plain washers when mounting the idlers. This gives enough clearance for the belt and also helps to line up the inside track of the idlers with the pulley
- Mount the pulley so it is flush with the end of the motor shaft. Make sure the set screws are on the "inside" (closest to the 10ga steel plate) (see picture)
- in addition to a washer on both sides of the wheels, use 6 1/8" spacers. This gives us enough space to span the makerslide which the 10ga plate rides on, and for the bolt heads that attache the z-axis delrin nut clear the front of the makerslide.
- on the front plate (aluminum) Be sure to use 1 extra washer on the outside of the wheels. This gives enough room for the makerslide that is the z-axis to clear the delrin nut.