Next Tool Project…A CNC Laser Cutter
by John
The Southworth steam powered boiler feed pump has many gaskets. I have not counted them, but there must be 15-20. All with many 2mm and 4mm holes.
And in the process of making the machine, I have broken quite a few of them with the multiple assemblies and tear downs.
But, fortunately, 2 of the members of my model engineering club have laser CNC cutters, so extra sets of gaskets has not been an impossible ask. (Thank you Brendan and Stuart!)
So, some time ago I asked Stuart, if it would be possible to attach a laser cutter to the CNC mill. His initial answer was NO. But recently, he changed his tune. He attached a laser head to his 3D printed CNC mill and started producing gaskets on request! So, as is a recent pattern, I am walking in Stuart’s footsteps, and I have purchased a 15 watt laser head on Ebay. Chinese of course.
This is the kit. Cost $AuD146.
And this is the 15w laser head. Now I have to work out how to attach it to my mill. Shouldn’t be too difficult, as long as I don’t turn on the spindle while it is attached.
My CNC mill, during the electronics upgrade. Most recent photo. Soon to have a laser head.
Stuart assures me that Mach3 can be configured to operate the laser…. turn it on and off, move the axes at an appropriate speed, etc. I think that some trickery is involved.
And future gaskets will be as simple as ….
So watch this space .
johnsmachines 
Hi John
Really interested in this laser cutter as I am in your position of having to cut many small gaskets for my next model. I will probably do like you and build something to attach to the mill using Mach3 so I am keen to see your approach.
Cheers
John Emery
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Hi John, I got onto your blog accidentally, and I would like to subscribe because it looks really interesting, but now I can’t find it. Please send the name and I will subscribe, and post a link on my blog. JohnV
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Hi John
I do not think I am going to continue the blog I have not added much to it the last couple of months I did not completely understand how to post correctly and finding time to do it was very frustrating.
My site is emersmodels.com the site name is a play on my surname I do not particularly like my site name ( it was a rush decision) but do not know the best way to change it so I have till end of November to decide weather to keep the site or dump it.
Have a look and let me know what you think
Cheers
John Emery
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Hi John, I liked the entries. The metal spinning was particularly interesting. Maybe could have had some more detail.
Thing is, you have to enjoy the writing and creating the post. If not, I suggest that you forget it.
I quite enjoy the process. The feedback from readers is the best bit, but that comes gradually.
Your work, photography, and subject matter is excellent. I would certainly subscribe if you keep up the blog. John
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John,
I’ve just started building a 4inch Southworth duplex pump – nice little sub-project to be used on the 7-1/4″ loco. Proceeding well, but then started worrying about the gaskets. They are not shown on the plans, just a note to use 1/32 material “as needed”. Many of them are obvious, but the number used on the steam chest stack, which I think is 4, amounts to a sizable thickness to to be missing from the plan. So, googling around, I came across your blog and instanmtly liked the laser cutting idea. Needing very little excuse to buy another tool, I reckoned less than $200 US was not bad for a laser cutter, so I bought one. Since then, come to find out China has its own unit of power, still called the Watt, but about 1/10th the size of ours.
Anyhow, I tried it out on a small sample gasket, to find that it takes forever to cut green aramid/buna material even 1/64th thick, which was my favourite. I also tried some fiber gasket and that seemed to burn up with more than 20% power and left a large kerf. Maybe my laser is underpowered, or somehow defective, so looking for a bit more info from your experiences, if you don’t mind?
I’d be keen to know what type of laser (wavelength and power) you are using. Also what kind of settings you use, like power, speed and number of passes. Also the gasket material you are using. Mine all look either black or green, but yours looks straw yellow. Finally, can you estimate the size of the kerf? Maybe by measuring how much under the desired size the finished item is?
Thanks in advance for any light you can shed. BTW, I’m located in Massachusetts (still can’t spell that after 38 years here!).
Regards,
Jed Weare
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Leave that one with me Jed. My friend Stuart cut the gaskets for me so I will contact him to get the answers. watch this space. John.
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John,
Just a follow-up that might help someone a bit. I persevered with the laser cutter and found the type of gasket material is, in fact, critical, as well as the settings for the cut. I thought about it for a bit and noticed that the laser in my cutter is a 400 – 445 nM wavelength, or blue-green. I remembered my physics teacher telling us an object’s colour is the colour of the light it does NOT absorb, then it dawned on me green was not a great colour to be using; most of the energy would be reflected and cutting. So for the first time ever I purchased some engineering material by colour! Felt like a dressmaker.
I bought some Fel-Pro 3045 from Amazon for the princely sum of $5 US. Three square feet of 1/64th inch thick. The material is called Karropak and seems to be a tan-coloured smooth paper material. At least it smells like burning paper rather than like burning rubber when being cut. It cuts much easier than the green stuff (aramid I think is the material). If anyone wants to try with a similar laser cutter, I found that 50% power (of 20W) and a speed of 650 mm/min cut clean through in 4 passes with good results. Cutting the four gaskets for the water cylinder covers took only 2.5 minutes. The cut quality was pretty good. Alternatively, 5 passes at 200 mm/min and 15% power also work, but the cut edges are not so clean.
Incidentally, my crack about Chinese watts is a bit embarrassing: turns out I had the max power value setting wrong, so the laser was only working at 1/4 power. At full power, that thing can easily start fires or blind someone, so you have to take care. There are NO safety devices to stop you doing stupid stuff.
Well, I just did three sets of very nice gaskets for the Southworth pump while penning this comment, so I reckon it turned out to be a pretty good investment. Still have $4 worth of gasket material, too.
Take care,
Jed
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That is excellent Jed. Would you mind if I use your comment as the basis for a post? John
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