So, it looks like I’ll be using the CNC head a lot, but the problem I’m running into is that there aren’t enough holes in enough places to securely clamp the wide variety of blanks I want to cut.
Does anyone know of an alternative build plate that has far more holes for screwing the clamping screws to?
At the moment, I don’t have the ability to drill and tap new holes myself, so there’s nothing I do custom right now…
Well, you do have this tool that can move to specific coordinates and carve holes. Nothing stopping you from drilling holes in the waste board and pushing a bolt though from below.
Make as many holes as needed.
Alternatively, you can make a hole large enough for a press fit dowel that you use for work positioning and clamp down using the existing clamps.
You can combine the two methods as required.
You can also carve out a negative for your blank and place that, holding it down as required.
I changed my SM1 bed and its clamps. I am happy now. Drilling holes was made easier by having a pillar drill and tapping by hand, providing you use some cutting fluid is not difficult, but it is time consuming. I bought a bar of T6 6063 aluminium for the clamps and a sheet of T6 6061 aluminium that was 4mm thick. It replicates the existing bed. The use of a hacksaw and file and the determination to make a difference to the original SM1 bed was all that was required.
I thought the CNC process could do with flat clamps so I made a jig that incorporated them and it works really well. The dimensions of the jig are 150 x 200mm, which is larger than the 130mm square of the supplied table but keeping the enclosure door open and placing the fixings at one end permits enough travel for the module to traverse the centre of the jig.
I ended up printing a bunch of these:
They really help with the reach and if I accidentally cut into them it won’t hurt the bit.
The only problem was the standard one was sometimes a little big and with SM you have to worry about running into Z-pillars. So I also ended up importing them into tinkercad and creating some 1/2 and 3/4 sizes. (I need to upload the remixes still) That gives me a ton of choice while still using the current holes.
Eventually when I need to replace the wasteboard I’ll probably go with a slot system.
-S
Yes, those are very nicely made. What is the method for using them on something that is 40mm in height?
Longer screws. Doesn’t matter if clamp touches bed, although I prefer it
-S
OK. I assume that is uses just a single screw. I really like how the red screw holding section is cleverly keyed to prevent it from migrating as it is tightened and its wedge shape keeps the line of the screw vertical. The slope of the grey clamp keeps it out of the way of a moving endmill bit too.
I was just considering the mechanical forces being applied as a sideways load from bits sized from 6.35 to 9.53mm in diameter. (my new trim router will accept these sized bits) My newly ordered CNC machine comes with a 710W trim router. Power will be around 0.952 kW at an angular speed of 30,000 rpm. Taking 0.952kW @ 30,000 rpm = 0.3Nm and at 10,000rpm it will be equal to around .90Nm.
I found the clamps that originally came with the SM1 to be soft and somewhat flimsy. The clamp design was not the most user friendly and it intruded a fair amount into SM1’s very restricted CNC workspace (90mm square).
I also found holding the original SM1 clamps and trying to tighten/adjust two set screws was quite awkward. My own modified clamp design has simplified the clamping process without intruding more than 5mm into the workpiece surface area. Additionally, the clamps are made from T6 aluminium which is non distorting, they don’t mark the workpiece and the line of force through the clamp and the additional spacers makes reasonable engineering sense to me.