Haas SMM2 w SMTC - Low air pressure after several tool changes. (Newb with questions)
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  1. #1
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    Default Haas SMM2 w SMTC - Low air pressure after several tool changes. (Newb with questions)

    Hi all. Just got a new-to-me 2010 SMM2 with a side mount tool changer. First real CNC machine for me, and first Haas. This machine will only be used for prototyping, no production.

    Machine just got set up and I'm starting to learn the controller but I've been running into a "low air pressure" alarm at some tool changes. I've searched this forum and others, watched the Haas videos on this alarm, and tried to do some debugging but I still have an issue (I think) so I'm wondering if anyone here has input.

    I'm using a model 10020DCAD air compressor by California Air Tools. The compressor is rated:
    - 2HP
    - 5.2 CFM at 90psi (I wrote CAT and they verified it would put out 4CFM at 100psi, per my machine's spec)
    - 10 gallon tank
    California Air Tools - The Largest Manufacture of Ultra Quiet, Oil-Free & Lightweight Air Compressors - CAT-10020DC

    The compressor is located in an attic space just outside of my shop and there's about 40~50' of 1/2" Rapid Air line running from the compressor to the machine. The max tank pressure is about ~130psi at shutoff, and the line pressure is regulated to 100psi. I've got the machine regulator set at 85~90psi per spec.

    Here's the issue. When I run a simple program of a series of eight changes one after the other (at 25% rapid) the machine gets through about 5~6 changes but then errors out with the low pressure alarm. On the last tool change before failure, the arm moves to the spindle and you hear an air venting sound but it just stays open. It hangs there like that for ~10 seconds and then alarms out. Will attach some pics of the various connections and video link below (note pic shows tank pressure only at 70psi - was during initial charge; it's set to fill to 130psi). It seems to get through 2~3 changes at 50% rapid.

    I originally had quick disconnects at the compressor and machine but I read those can be choke points so I've removed all of those. So, there is no restriction smaller than what's on the compressor or the machine regulator (I think both are 3/8"). Again, the air line itself is 1/2". I checked the filter in the machine's water trap to see if that was clogged but it appears to have been removed entirely (yes, I'll get a replacement) so obviously that's not impeding air flow. In the video you can see that the initial pressure is ~90psi, then during tool changes it's just over 80psi and drops momentarily to ~70 psi during the change. After a few tool changes I can hear the compressor kick on (kicks on ~90psi tank pressure) and that's when the tool change fails. So, it seems like the tool changes work when the machine is pulling from the compressor tank, but when the compressor is actively refilling the tool change fails.

    So, my questions are
    - Is this really an issue? I'm not sure when I'd ever do 8 tool changes in rapid succession but what worries me is that this is a sign of an air supply issue that may bite me in the middle of a program. Like, maybe I'm using the air gun to blow something off, which drains the tank to the recharge point and then, at that moment, if the machine calls a tool change it'll fail. Or, is something like this pretty unlikely?
    - If this is something to address is my issue the compressor or could it be a machine issue (pressure switch or something)? If the problem is the compressor, do I need something that can actively pump more air (more HP), something with a bigger tank, or both?
    - I've read about others adding a second "accumulator" tank at the machine to address low pressure issues. Do you think this would do it? And if so, where should that accumulator tank go - before or after the machine regulator? How big an accumulator would you recommend?

    I thought I'd read of others with mini mills that were using even smaller compressors successfully, so I'm a bit surprised but this issue. Thanks for any input! Looking forward to making chips with this machine.

    2019-04-10-15.43.16.jpg
    2019-04-10-15.42.59.jpg
    2019-04-10-15.41.02.jpg
    haas-air-manifold-machine.jpg
    https://miks.smugmug.com/Haas-stuff/...tuff/i-r6Lh3QP

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    only thing I can say is trash the POS air compressor and buy one with a bigger tank and more HP.
    you got 20k-40k+ tied up in the mill and tooling yet you have a bicycle pump for a compressor.

    A compressor is the heart of your machine,

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    you need a air tank right at the machine, I found little 8 gallon tanks on ebay for like $60 that are made for cars,, I run air hoses to them then put 1/2" PEX pipe between them and the machine ,,, My vf4ss alarmed out tell I added the extra tank ... the tool changer need a LOT of air fast and a long air hose just cant keep up ,,, your compressor should be fine in that I can run 3 Haas mills off a little 3/4HP Emglo compressor and have done it for years.

    Any tank well work at the machine but the small car tanks are short so you can put them under the right hand side of the machine.

    ( even if you go to a bigger compressor your still going to need the tank at the machine so try it first with your small pump)

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    D.D.Machine - thanks for the tip. I’ll give it a shot before getting a bigger compressor. One question: do you put this extra tank *before* or *after* the air regulator at the back of the machine? In other words, does the extra tank go between the compressor and mill’s regulator, or between the mill’s regulator and the machine itself? Or maybe it doesn’t matter? Thanks again!

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    9 Gallon Steel Air Tank 8 Port Air Bag Suspension Train Horn Air Ride Kit | eBay

    there is 3/8" holes in the mounting feet and I just ran like 3" bolts in them with double nuts to make feet so the tank is up off the floor so I could drain in every few weeks and put a cheap harber freight filter on the outlet side feeding the PEX pipe ,,, you well want to fill the tank at one end and put the filter at the other end ,, I put in 3/4" black steel pipe running around the walls in the shop and there is 80 feet of pipe before the risers for the hoses going to the machines ,,, 99% of the water gets cought in the drops and I found I only need to drain the water every few weeks and the all the pipes are slanted 1" per 10 feet so even if a drop pipe gets full it just runs back to the compressor tanks and cant ever get up into the risers.

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    I just have one regulator and its on the compressor outlet. you don`t want a regulator between the tank at the machine and the machine. Regulators slow down air flow and that's the last thing you want to do ... the tool changer needs it shot of air flow FAST ,,, well the tool retention cylinder does not take a large amount of air to open the retention fingers that grip the pull stub it does need it FAST.

    Air is measured two ways, by pressure and by volume ... you can have 125+ PSI at your compressor tank but if you cant keep up with the volume at the machine then your air pressure well drop at the machine .. thatis what giving you the alarm ...

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    D.D. Machine - thanks for the link and extra info. I appreciate it. I'll try to get an extra tank plumbed in at the machine (I'm still not sure if that goes before or after the regulator bolted to the machine but my guess is it may not matter that much). Thanks again for all your input.

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    I'd probably put it before the machine regulator. The reg has plenty of flow for the machine, otherwise there would be a lot of people with big compressors still running into problems. The less you can modify the machine, the better.

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    Npolanosky - that makes sense. I'll add it before the regulator and see if it addresses my issue. Thanks.

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    Harbor freight has 5 gal tanks for $30.00 and 11 gal tanks for $40.00. I put a 5 gal one on each of my machines.

    You will also find you loose a lot of pressure from friction in running air in a half inch line for 50 feet. There will probably be a 10 lb drop during full flow.

    Also, the compressor's regulator has a 130lb cut-out, but what is the cut-in? Probably between 85 and 95, so when you get heavy use, the working pressure at the machine will be even lower.

    Get a tank first and that will probably work for you. Most machines have a T-fitting where the air comes in and I just plugged my tanks in there. You do want it before any regulators, straight from the compressor.

    Later, a better compressor would be a good idea. And, an air dryer is almost a necessity. Got mine at Harbor Freight also, less than $400.00 and its been running over 4 years.

    Good luck---Mike

    Search results for: 'compressed air tank'

    Compressed Air Dryer - Save on this Compressed Air Dryer use a 20 or 25% off coupon!

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    all of the harber freight tanks I have seen just have a "SINGLE" NPT hole to work with ... thats why I went to the car air tanks in that I wanted a inlet , outlet and drain hole ......

    with only one hole like the harber freight tanks they well fill with water and be hard to drain .

    I have found over the years that regulators seem to go bad over time and when I put in the new shop I just did "ONE" regulator right at the compressor and just keep a new spare next to it ..

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    For a band-aid fix, you could increase pressure to the machine up to around 100psi. It won't hurt, in fact the machine has an alarm if pressure goes too high, just as it does with being too low.

    But yeah, definitely need a bigger compressor. With your current setup it's just on the brink of being starved at all times. Be cautious with adding accumulators to store air volume, because a small compressor will be running a long cycle to full up the added volume. (might want to check the duty cycle on it, like half-on-half-off)

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    YdnaD - thanks for the idea. I might try that. Agreed that the real fix is a bigger compressor. I think the 40~50' of 1/2" line, coupled with the lower HP of this compressor ends up giving me just barely enough pressure at the machine during recharge. I'll see if the 100psi at the machine helps but am on the hunt for a better compressor.


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