Thread: WIP 150mm Auto Blast Gate

The gate back and front needs to be taller to provide for something to lock the tops of back and front together - like this.

Screen Shot 2018-05-02 at 4.29.36 pm.jpg

Hello Downunder. It has been a VERRRY long time since I visited here in an active way, I but saw one of my favorite topics in the latest newsletter topic list. Some of you may remember me from old IBOX threads- I came up with the basic IBOX design and licensed it to INCRA. You might have figured that out by my user name. A quick update- the IBOX continues to sell well. Then, in addition to continuing with my hobby woodworking, I started to do some design work for a major manufacturer/importer on a big project, but I got ripped off, so I have done almost no design work and little woodworking since then The one exception is the little Lock Miter Master jig sold by Infinity Cutting Tools in Florida. The LMM makes setting the finicky lock miter router bit much easier. It was awarded a patent two years ago and continues to sell well.

Now as to dust collection- in the late 90's and beyond I got involved with Bill Pentz and the home cyclone craze. (Bill and I were actually investigating writing a dust collection book). I built a modified Wood Magazine cyclone to which I added an angled inlet ramp. After I retired, I moved and built a brand new shop. I also built a second cyclone using Bill's design, . . . . mostly. It has a 3D cone (the cone is three times the diameter of the cylinder instead of 1.64X.) According to ? Bill? it is supposed to do a better job separating the fines. I also configured it in the push-through mode- blower ahead of the cyclone- that way I don't need a tightly sealed dust drum, just a large (39 gal.) lawn trash bag attached to the bottom of the cone with a band strap. When it is full (I have a simple high dust alarm) I remove the bag and carry it to the curb for trash pickup. No messy job trying to empty a heavy, full drum. I still love it after almost 14 years! A year or two later I automated my old gates and new gates I needed for additional machines. I use CR Magnetics current sensor switches at each outlet where a machine plugs in. The current sensor switches allow 24V DC to be applied directly to 5-2 (5 port, 2 state) SMC solenoid air valves. Shop air, regulated to about 16 psi and distributed by cheap, low pressure vinyl tubing, is ported to bi-directional Bimba pneumatic cylinders which operate each blast gate. Speed and force of gate action can be adjusted with air pressure and restrictor valves (needle valves)- from slow and steady to a fast guillotine that can literally remove a finger! When a machine is on, its blast gate is open. When a gate is manually (I have push on/push off buttons near each gate for manual operation) or automatically opened, it triggers the dust collector motor. To avoid excessive cycling of the dust collector motor, I designed the circuit so I must manually turn off the motor (I could have used a delay-on-off relay.) Current sensor switches, solenoid valves, and cylinders all came from eBay or other surplus sources. My simple, self-cleaning, easy-sliding blast gates are guillotine style- inside faces are laminate over MDF; the slide is made from two layers of laminate bonded back-to-back (I wrote a blast gate article that was published in AWW - it may still be floating around the web.) To convert them to autogates, I just attached a pneumatic cylinder to the gate body and the actuator rod to the gate slide. There used to be a video about it on the American Woodworker Magazine website, but it has since ceased publication and the site closed. I can't find the original video either! I have posted about it numerous times on US WW forums- primarily North Carolina Woodworker and Sawmill Creek, but also on Wood Central, Woodnet, etc.

Except for using Arduino, PLC, etc. not too much has changed in home dust collection. In fact, some of the same construction and operation questions and designs appear to have made it full circle and are showing up again from new/younger woodworkers.

Anyway here are my two cents worth:

Butterfly blast gates- hard to seal against walls- many PVC and metal duct are not smooth, metal has a seam, etc. Except initial movement it shouldn't require much force to overcome initial resistance. Long fillament shavings could catch, clog, or jam the gate. An open gate will cause resistance and create turbulence. Rotary activation could be a problem. If you use an electric solenoid, motor, gear motor, etc. to operate the gates, you need enough torque, moment arm, throw and a way to control motion (physical and current limit switches) and prevent stalling which could cause overheating (and failure and/or fire.) No such problem with pneumatic gates.

Electronic control iis OK if you have the knowledge and like that sort of thing. Cost and complexity could easily get out of control.

My thought about the purpose of autogates- I'm lazy, and didn't want to worry about opening the machine gate- same goes for closing the gate, except when I'm jumping from TS to jointer and back. I think having the gate state determine whether a machine can be turned on is totally unnecessary.

Originally Posted by BobL

The gate back and front needs to be taller to provide for something to lock the tops of back and front together - like this.

Screen Shot 2018-05-02 at 4.29.36 pm.jpg

Yes, that’s missing because due to my lack of prowess at the moment with Fusion 360. It’s the first attempt at a model without reference to a tutorial. I intend to rebuild from scratch to aid learning.


Sent from my iPhone using Tapatalk

Originally Posted by arniew

Yes, that’s missing because due to my lack of prowess at the moment with Fusion 360. It’s the first attempt at a model without reference to a tutorial. I intend to rebuild from scratch to aid learning.


Sent from my iPhone using Tapatalk

Hi....just curious, have you made any further progress with your design?

I’ve just about got a prototype ready for testing. I’ve been gathering components for the electronics required but the first proof of concept will be simple switching. I’m about to order a CV1800 to give it a real life test with air flow and blocking of same. I’m not sure my old DE is going to be up for the job. I’m currently moving workshop and the blast gates are destined for the new place along with the CV DE.


Sent from my iPhone using Tapatalk

Originally Posted by arniew

I’ve just about got a prototype ready for testing. I’ve been gathering components for the electronics required but the first proof of concept will be simple switching. I’m about to order a CV1800 to give it a real life test with air flow and blocking of same. I’m not sure my old DE is going to be up for the job. I’m currently moving workshop and the blast gates are destined for the new place along with the CV DE.


Sent from my iPhone using Tapatalk

Thanks
I love automation and when i don't get time to do it i look at others doing their's....

I've been testing a prototype gate with a couple of different motors I had on hand. The first one promised to have enough torque but didn't quite go the journey. It was a geared motor at 10RPM (or about two seconds to open/close a rocker gate). The second test was with a linear actuator, with 50mm travel in about two seconds. I'm happy to say this looks good. It hasn't been tested with a DE behind it, and I need to tighten the linkages a little, but it looks promising.

I've got a CV1800 on the way so will test it soon under real conditions.

I've received my current sensing transformers so the next step is controlling a gate to open when a machine is turned on.

The bigger plan is to use a mesh network of smaller gate controllers allowing the system to be expandable to cope with larger systems. I've put in a pre-order on these, but it will be a couple of months yet before they ship.

Here is a short video showing the prototype in operation.

Hi there

What about a slide gate with a linear actuator, like an air cylinder. That way there is no restriction when the gate is open and seals off fully when it is closed. It could be driven by a solenoid valve with a 24V coil.

Just a thought. Well done for giving it a go.

Originally Posted by Graham99

Hi there

What about a slide gate with a linear actuator, like an air cylinder. That way there is no restriction when the gate is open and seals off fully when it is closed. It could be driven by a solenoid valve with a 24V coil.

Just a thought. Well done for giving it a go.

Hi Graham99,

I'm not sure what you mean about restriction and sealing. The rocker mechanism seems to do both.

I know there are others who have gone the air cylinder route. It seemed to be as costly (or more) to do that and added a complexity due to the need for electric control and an air supply. While I have a compressor, I'm not that keen on firing it up every time I'm using the DE. My background is in electrical engineering, so it's also more my comfort zone.

I'd love to hear more about alternate ideas before I am too committed to a particular way though.

Originally Posted by arniew

I know there are others who have gone the air cylinder route. It seemed to be as costly (or more) to do that and added a complexity due to the need for electric control and an air supply. While I have a compressor, I'm not that keen on firing it up every time I'm using the DE. My background is in electrical engineering, so it's also more my comfort zone.

It's easy enough to leave a compressor on a timer circuit that auto starts at say 8 am each day and turns it off at 6pm, or over a time period that suits you. A close to air tight system should not need to recharge all that often because pneumatics uses very little flow and operationally not expensive since a 90s recharge by a 3 kW compressor costs about 2c.

At work we had compressed air "on tap" but it was not always available so on one machine we installed a dedicated 1.5kW compressor with a 10L tank that operated 7 pneumatic valves on the and that used to recharge about once per day.

Because I spend much of day in my shed I leave my compressor on 24/7 and have compressed air reticulated to 7 points around the shed so I never have to wait for the compressor to start. Also no matter where I stand in my shed I am not more than ~3m from a compressed air line. I got so used to having compressed air on tap at work this became a "must have in my shed item" on my shed list for when I retired. I reckon this approach is one of the most useful things that can easily be set up in most DIY sheds.

Well it's been a while (moving, new job, renovating etc.) but I can report some progress. Some time ago I built a rocker style gate that I could drive with a linear actuator. The actuator I have moves 30mm/s and is 50mm long. Mid last year I was able to get it to work effectively on the bench, but with moving I've had to wait for a real-world test.

I've now installed a CV-1800 and finally got around to testing the gate today. I'm very happy to report the actuator had no trouble opening and closing with the DE in full flight.

The actuator I'm using sells on ebay for about $40, and it may be possible to find a cheaper source for bulk items. I've had a good look at this thread by maxxsinner - New workshop dust extraction install - build blog and it seems to me that per gate it would cost about $120 for a pneumatic relay and air cylinder. The set up I'm working on would be less that $50 per gate. (I'm not taking into account a controller or sensors/switches to demand a gate open).

So, before I run headlong into spending my $, a question for those who advocate for compressed air over electrical solutions. Am I missing something, or is that roughly what it would cost to drive a gate? Is there anything else I'm missing?

I haven't looked at automated blast gates costs for a couple of years but I remember finding some half decent pneumatics being made in indonesia that would have been OK for DIY use and I don't recall them being more than about $40 for the pneumatics per gate. One disadvantage with pneumatic systems is that it assumes a compressor is on at all times. This is alright for me but wouldn't it be a PITA if you had to wait for the comp to charge up.

I put my auto blast gate development on hold because most of my existing 17 (PVC and MDF) gates are too compact and would need to be remade again from scratch to suit either pneumatic or electrical actuators. I made those 17 gates over a period of about 6 years and I couldn't justify spending the time or money on remaking them again. Last year I devoted my limited dust extraction upgrading time and $ to upgrading the 3HP DC motor to a 4HP motor with VFD which has been a real success.

In the interim I have installed simple vacuum switches on the ducting to the 5 main dust makers in my shed and find these to be extremely effective in requiring me to have the DC on and to open the right gate valves otherwise the machine won't start.

I'l be interested to hear/see how your real world test goes. What I found with the automated Al rocker prototype I built was it worked fine on the bench but the higher friction induced by the DC vacuum on the Al was a big problem and I would not consider using Al for gates in the future.

I have some half arsed designs in Fusion 360 at the moment. I am hoping to 3d print some blast gates at some point. Still working on a cheap way of doing it using DIY linear actuators. Been taking a lot of ideas from thingiverse. Life is just getting in the way at the moment!

I did manage an hour in the shed today, first time in about 3 months.

I'm finally about to launch into a build of linear actuated rocker style blast gates. I've been happy with the prototype I built last year. IMG-1099.jpg

The rockers are built from whiteline 3mm MDF with a melamine coating one side. I've laminated two of these back to back with the melamine to the outside. IMG-1081.jpg

The front and back (body) parts of the gate are laminated with whiteline (melamine facing inwards) and 12 mm ply. IMG-1082.jpg

This way the moving surfaces are coated with melamine. I've found the rocker to be sufficiently rigid in a couple of months use with my CV1800 extractor. The linear actuator seems to have no trouble opening and closing the gate. IMG-1098.jpg

I will make the gates as a batch lot and work on the control side of it as a next step.