Currently building my Altmill 2x4 and im at the point where I need to get the Table Bed and Spoilboards ready.
The manual calls for a 3/4" MDF for the table bed and Im assuming that this is normal for standard builds. Is the main purpose for the table bed so that its a flat surface for the spoil board to mount to?
If so, then aside from cost, is there a reason why i couldn’t use material thats not 3/4" MDF? Can I use a 1/4" aluminum plate? ACM panel? Aluminum Honeycomb? Maybe even steel-reinforced plywood and then just surface the top layer?
Asking because I have a lot of materials around that i think I can use as alternative.
I plan on using MDF and T tracks for my spoilboards/Spoilboards’ spoilboard.
Other people have used aluminum plate (and drilled and tapped a million holes for attaching things).
Yes, it’s main (only?) purpose is to provide a flat support for the spoilboard.
Is there a general expectation on how often we would need to maintain the table bed? Once it has been trammed and made flat with respect to the CNC, it generally doesnt need to be reworked unless the bit cuts past the SB and into the bed correct?
Correct. Please note that ‘trammed and made flat’ is a ‘nice to have’ rather than a requirement. The spoilboard is what is critical. Also, it really doesn’t matter what the spoilboard looks like. The very first thing you do is you skim-cut the spoilboard which makes sure that it is parallel to the mill.
If the main table is flat it optimizes the support for the spoilboard but even if it has a big divot in it, it will not affect the end result because the spoilboard surface will be parallel to the mill.
AFAIK, the people that have used aluminum plate have done so because they wanted to mill aluminum and possibly use coolant which of course you can’t do with an MDF spoilboard.
As a side point, wood moves so if you want accurate results you should re-surface the spoil board regularly. I seem to recall having heard that commercial shops do this routinely as the first thing at the start of the day. I am not sure how true that is but I do a re-surface whenever I want the best results. It may only be 0.2 mm … just make sure that material is removed from the ENTIRE spoil board. I usually use a pencil and scribble all over the spoilboard and if any part of the scribles remains after a re-surface, I know I need to do another re-surface pass.
@ReveriumDesigns You don’t need to make the table flat. Just make sure it’s properly fastened to the rails and you should be good.
The spoil board on the other hand, you will need to surface. Not necessarily to make it flat, but to make every point on the board be at the same distance from the spindle. Your spoil board may not be level and may have a twist from one corner to the other but those are generally not important considerations for the mill’s intended purpose (woodworking). What is important is the constant height from the spindle to the bed.
If you were precision machining metal, then flat and level are important. But that’s not what the Altmill is for.
@ReveriumDesigns I’ll just add to the previous posts that you should keep in mind that it you use a table top material that does not easily take screws, you will need to come up with a another way to hold down your t-tracks and spoilboard slats.