I've recently started working for a company, programming for their Busellato. I don't have any experience on this particular machine (only on Thermwood CNC router).
They are having a problem with their dowels lining up - decks not flush with gables. Is anyone out there using a Busellato for dowel construction? Is it precise? It was suggested to set the decks and tops so that they are approximately 1/8 from the edge, but this is not acceptable for the type of projects we are working on (all commercial casework). It was also suggested to cut the parts oversized, then let the machine cut them more precise, then do the doweling, but this is adding an extra step. (We do not have a beamsaw.)
I have a few theories as to why it's not working, one being that the drill heads were crashed and damaged, then fixed and calibrated. The parts can be reversed to use the other drill heads, but some of our parts are too long. We have adjusted the heads on the machine, which works at first, then you try it again later, and it's off again. Also inconsistent material thicknesses, etc.
Any tips would be greatly appreciated. We're looking at having our supplier check out the previously damaged heads again.
From contributor D:
The machine is very accurate. You have several other things going on that might cause a problem.
Material thickness problems: always make sure the dowel joint is accurately referenced to the outside of the case. If it is not, the variations will show up as misaligned dowel joints.
Tooling: if you have an accurate drill, the hole is going to be perfect; if not, the drill will wander, or the hole will be inaccurate in size.
Support: be sure the panel is supported close to the edge, or the drilling operation could deflect it, causing a misaligned dowel joint.
Vacuum pods on the support benches: make sure there is an accurate support under the panel and that the vacuum is pulling the panel all the way down flat.
You should test drill parts to find out the cause of the problem. Then it will be easier to solve.
Aside from that... trying to do flush construction (which is what is sounds like you are doing) is the most difficult type of construction, especially with dowels, because they are so unforgiving. If you use small reveals (1/8" or less), it works very well, and the reveals absorb and hide subtle variations.
As pointed out, you need to keep track of the reference face from horizontal drilling of a part to assembly. It is too easy to reverse or flip a part if you are using a centered dowel pattern and a T/2 center in the edge. One solution is to use small reveals (1/8" or less) as suggested, and don't worry about it. Another is to offset the drill pattern in an obvious way that the assembly only goes together.
You wrote: "It was also suggested to cut the parts oversized, then let the machine cut them more precise, then do the doweling, but this is adding an extra step. (We do not have a beamsaw)."
I think what someone might have suggested is to let the Busellato machine the part using a milling past, prior to any of the drilling operations. This is not adding another step - the part is on the machine one time, but to guarantee the part is accurate and square is something you must add to your evaluation. How many poor parts produced does it take to offset the value of another line of code?
You should have some additional training on the machine programming. It is a simple machine, for sure, but Delmac has a good training program if you get a hold of them.
Comment from contributor O:
I run a Jet 200 and have encountered the same issue. For me it came down to tooling. When nesting parts, and most other times, tool diameter is very important. My nesting software has a setting for tool diameter. It lays everything out according to that value. If my diameter in the software is not the same as the actual diameter of the bit being used, tolerances are off.
I make a simple calibration tool-pass to check my bit length and diameter of cut. Donít trust the bit manufacturer, check it yourself with calipers. A 1/2 inch compression bit may not be 12.7mm it may actually be 12.5 or 12.4. If the actual diameter is 3/10mm less, then your parts will be 6/10 off in finished width. The machine does not know until you tell it. I also have lost 2/10mm just from use. So check your bits occasionally.