The Altmill comes with a dust chute for a 4" hose. That said, does it really need a 4" dust collection system ? Would a system with 2" or 2.5" hoses work equally well without getting clogged ? Knowing that will give me a starting point for researching the actual vacuum or dust collection system. I’d use a cyclone separator as well. I have a Shopvac but it’s loud and not really made for extended use. So I’ll be looking for a long term alternative. TIA
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Hello!
@Chucky_ott there are a number of threads here, mine included. While I don’t have an AltMill, my experience with my LongMill are applicable. I use a 2.5” hose that seems to work appropriately and not clog. I leave a blast gate slightly open to minimize the work on the single stage dust collector with cyclone that I use. Would I prefer a 4” hose? Yes, cause you go big or go home​:joy:
. Depending on what you will be doing with your AltMill, a 4” dust hose would be beneficial for you. Hit some of the vendors of dust collectors. Clearview, Oneida are at the top of my list. Personally, I have a chip collector that pretends to be a dust collector. It is a single stage with a bag filter. It is a Jet 1100. With the cyclone from Oneida. It is MUCH better. You can pick them up used quite frequently for little money. Once I get back out into the shop, they do make a 1 micron can filter to replace the bag. One last thing, minimize flexible hose. Ductwork as close as you can and then transition to flexible hose.
Read on!
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Yeah, I had seen most of them but they don’t really address the duct size for the Altmill. One thing is certain, the duct size needs to be sized to the CFM of your vacuum/extractor. Too large a pipe will result in inadequate air flow in the pipe, resulting in clogging. Using 4" ducts with an underpowered vacuum will likely clog more than using 2" ducts. In other words, the whole system needs to be designed properly.
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Oneida air is a good resource for that. My system gets bogged down when I use my 2.5” hose without opening up a blast gate.
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I can tell you that 4" hose on a dust collector (not shop vac) is the way to go. Shop vacs have high suction, but low CFMs. Dust collections are the opposite. if you reduce to 2 1/2" you reduce the CFMs quite a bit. I have a long mill with the spindle. I used the Makita and 2 1/2" hose for a few years. Once I had the 4" on the spindle, I had almost no dust escaping. This is especially noticeable on surfacing with larger bits. Check out Busy Bee tools for dust collectors and cyclones.
Reducing from 4" to 2.5" will reduce the CFM if you use a HVLP dust collector. I don’t think that’s the case if you use a LVHP system like the Record Power Camvac. But a LVHP system is better with dust than with chips. Question is, does the CNC produce large dust or small chips?
Depends on what you are machining and with what you are machining it with.
I found vcarve and finishing pass with ball/tapered will produce mostly dust. Roughing makes chips. MDF is dust all the way.
I personaly think I would like to catch the dust more than the chips, if I was working in the same room as my machine. I don’t, so I don’t bother with a vac at all on my mill after I banned MDF from ever again being milled on my machine.
Agreed. I mainly want to catch dust too. Chips I can sweep off the floor. From what I understand, most Shop-vacs are LVHP systems. They will probably work well if you stick with the 2" duct that they are designed for. Perhaps not so much if you upsize the duct to 4". The Camvac is a 2-motor 4" LVHP system and has an air flow of 573CFM according to the Canadian distributor (specs from manufacturer is about half at 228 CFM). But the dB rating is 68, much lower than a Shop-Vac. Unfortunately, it runs on 230V.
@Chucky_ott One thing to keep in mind when considering shop vacs is that they are not designed to run for several hours at a time. Just sayin’.
Correct. Hence the use of the Camvac. It’s not a shop vac but a LVHP dust extractor. Unfortunately, the duty cycle is not specified so no idea how long they’re designed to run,
@Chucky_ott Understood. FWIW, I run a very old 2hp craftex dust collector. I run a 4" flex line from the duct collector to a quick disconnect on a 4" solid pvc pipe at the left front of my Long Mill table. (the quick disconnect is there so that I can run the flex to all my other shop machines) The 4" pvc runs horizontally to the back of the table, then up about 5’ or so, then horizontal again to the centre of the table. From there, I run a 2.5" flex hose to the dust shoe.
No matter what the material, there is not much of anything left on the table. I have found that the biggest issue in dust collection in a wood shop - be it jointers, table saws, planers or CNC machines is the effectiveness of the port on the machine. That holds especially true for a CNC. If the dust shoe is not a good design, all the volume in the world is not going to give good results.
Just my humble opinion.
yeah, maybe everyone who built an enclosure figured that one out.
@Chucky_ott Maybe. I don’t like the enclosure idea since, no matter how well designed, it takes away from the ability to get to all areas of the table.
I don’t understand at all the idea of using an enclosure as the rationale for having the router/spindle fling chips and dust everywhere inside it, only to need to vacuum it up later. Vacuum it out of the t-tracks, out of the lead screws (Long Mill) out from around the feet holding the gantries, out from any lights in the enclosure, out of any sound proofing in the enclosure… Why not collect it efficiently and effectively at the source?
All that said, I completely accept that there is no wrong or right way to accomplish the objective. In my case, since my shop is in the basement, the objective is to have as little dust in the air as possible.
Don’t tell my shop-vac that. It is 15 years old and has run on 10-30 hour carves. Only stopped to switch bits. 
. I run it through a dust right and It has a hepa filter in it with a drywall bag. Looking to upgrade to the new HB vacuum system this summer. Shop-vacs draw around 11 amps so
might as well save a few amps and go 4in to boot.
@deanberg For every “rule” there is an exception. 
“30 hour carves” ! You’re an animal.
15 years old is probably why it can run for so long. Newer machines…maybe not so much. Surprised the brushes on the motor haven’t worn out yet.
As for the Camvac, I downloaded their manual today and saw this: " Important: The machine must be turned off for 15 minutes after a maximum of 2 hours continuous use to avoid overheating the
motor. Failure to comply will invalidate the warranty"
But note that some models have two motors and others have three. For the two-motor model, you probably want to alternate between the two.
A very good article on the use of LPHV or HPLV in your shop.
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Yes the saying they don’t make them like that anymore is probably true. I did have to replace brushes in the Makita router a month ago so the vacuum is probably on it’s last leg. That hepa harbor freight setup will be the next step for me.