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Jolt & friends - Team Overkill - NSW
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Nick
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Joined: 16 Jun 2004
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Location: Sydney, NSW


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Winter Solstice:

Even though its the shortest day of the year, I got a fair amount done. Later on, I should make a sacrifice to the robo-gods to ensure a bountiful harvest of trophies at the up-coming events. Smile

CNC mill:

The steel column support plates are here and they weigh WAY more than predicted - 51Kg. The mill base only weighs 25Kg and then there is around 15Kg of epoxy cement to add into the equation. Between the extra weight, the dampening effect of the epoxy and the added stiffness, the parts finish should be noticeably better.



The next steps are to drill & tap the steel and work out the mixing ratio for the epoxy cement; both long & tedious tasks.

Laser cutter:

I found a new problem with the laser; one end of the X axis carriage is drooping out of alignment with the beam by about 5mm. That explains the huge power loss at the final mirror and no amount of realignment can fix it Mad. The only cure is to shim up the end of the X axis where it rests on the Y axis linear bearing. Its a really major job and might even involve cutting a hole in the case to get access. Or I could pretend it never happen end and just put up with a lower power laser.
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Post Wed Jun 21, 2017 6:09 pm 
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miles&Jules
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Kind of surprised by all the problems on your laser nick- did they even test it before it left the factory?
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Post Wed Jun 21, 2017 9:52 pm 
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Nick
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Their testing probably ends after they see the tube light up Rolling Eyes . Until now I wasn't too fussed about fixing little things like cheap mirrors or the poor air assist - that's what you get for one tenth the price of a name brand laser, plus I learnt plenty about the inner workings of the machine.

The off-axis problem is different; it means the whole frame of the laser is off by that much from left to right. It would have been easy to fix while the laser was being built buy that's obviously not part of their QA plan.

I might be able to fix it another way. All the linear rails are mounted on RHS aluminium tubes, so if there is easy access to the screws holding the Y axis tube, then I can shim up the whole right side of the gantry - photos coming soon.
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Post Wed Jun 21, 2017 10:03 pm 
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Nick
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This is the problem area:



I need to put a spacer between the green & red Y axis linear bearing and X axis tube above it. The screws holding the tube to the bearing are INSIDE the tube. There must be some access holes in the top of the tube, hidden under the stepper motor so that's the first thing to remove.

I realised that there is no need to cut a hole in the case above the stepper to allow access for Allen keys, they thoughtfully left a large hole for me:



Once the control panel is removed, the is much better access to the stepper and the bearing. So apart from getting the stepper reinstalled correctly, the work doesn't look as difficult as I thought.
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Post Wed Jun 21, 2017 10:40 pm 
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Nick
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CNC Mill:

The column support is progressing, but slowly due to some painful finger injuries.





The spacer and main plates are drilled & tapped and the next step is to use the main plate as a template to drill holes in the angle. The holes are an odd size so I am using this handy expanding transfer punch:


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Post Thu Jun 22, 2017 9:18 pm 
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pilleya



Joined: 31 Mar 2016
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Location: Sydney


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The good thing about you buying a laser is that when I purchase one( looking to do so reasonably soonish) I already know how much work I will need to put in and what to look out for. Smile

Approximately how much time and $$ have you put into the machine so far?

Post Fri Jun 23, 2017 12:28 am 
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Nick
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The 100W laser itself cost just under $3,700 and I have spent around $300 on upgrades. The time invested is never ending - there will always be some tweaking to be done, whether its really needed or not Wink

There are many eBay sellers offering similar machines; they are almost all the same company under different names. There are some cheaper lasers that ship direct from China; be careful comparing prices as the freight, GST and possibly import duty will jack their prices up. The locally stocked lasers all appear to ship from Sydney and you get fast delivery.
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Post Fri Jun 23, 2017 1:29 am 
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pilleya



Joined: 31 Mar 2016
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100w is a pretty powerful machine, you mentioned that you had been having trouble cutting 12ish wood. The machine I have access to( I made most of tumblers parts on it) is a Universal Laser Systems machine probably a good 6-7 years old with a 50 watt tube and it cuts 12mm MDF and plywood without any problems*

*With a freshly cleaned lens as it doesn't have air-assist so it can get dirty easily.
Also interestingly there is a big difference between types of MDF in how friendly they are to cut, the small pre-cut bunnings sheets cut much better than full sheets( they have a different colour and different texture).

Post Fri Jun 23, 2017 1:57 am 
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Nick
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The issue with cutting thick materials is mostly the short focal length lens that most of these lasers come with, the short focus means a higher power density at the focus point, so they cut like champs in thin material. Unfortunately, the power density in the beam falls off rapidly above & below the focus so on thicker materials you have to up the power and / or cut slower to get enough power all the way through the material. That usually means the top of the cut is totally incinerated. When I fit a longer focus lens, the thicker material will be much easier to cut.

The other issue is the "power fraud". Unless you get an expensive tube from a manufacturer like Reci, the real power output of Chinese lasers will be at least 15% lower than the stated power. My power meter shows the 100W tube really peaks at 84W, right in line with other user's results. A name brand laser probably puts out near to the stated power, so your 50W laser might be much closer to my 100W laser than you think.
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Post Fri Jun 23, 2017 11:54 am 
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Nick
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BTW: air assist is for much more than keeping the lens clean. Smoke absorbs the IR laser beam really well, so the faster you can blow the smoke out of the cut, the better the laser will work. Just increasing the air flow in my laser helped quite a bit and I will eventually replace all the tubing and fittings with larger parts to get more air flow from the pump.
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Post Fri Jun 23, 2017 12:01 pm 
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Jackbk



Joined: 07 Aug 2013
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Hey Nick,

Been following your build reports from the sidelines. Good stuff.

Quick question, do you get your TI locally or overseas?

Post Fri Jun 23, 2017 8:02 pm 
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Nick
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I don't know any local places that sell cut to size titanium - it all comes from Ti Joe in the US. They have a huge warehouse of Ti off-cuts but be warned the stock list isn't up to date so sometimes the perfect piece you need is already sold.
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Post Fri Jun 23, 2017 9:31 pm 
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Nick
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CNC Mill:

The screws arrived and I had a trial assembly of the column brace:



There is still a little work to do but everything fits. I can barely lift the assembled parts and will definitely need the hoist to get it attached to the mill. The epoxy concrete is progressing; all the materials are here but a slight snag is that the minimum temperature for the epoxy to set is 16 Deg. C and its barely cracked 13 degrees all week. I will have to get a large heater in the workshop and warm it up before any epoxy is mixed.
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Post Tue Jun 27, 2017 12:59 pm 
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miles&Jules
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Cool- what's the epoxy do is it for rigidness
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Miles Blow - Julie Pitts
www.mulesfilm.com.au
www.wombokforest.com.au

-Pickasso- Vivid Sportsman champion 2015

Post Tue Jun 27, 2017 1:07 pm 
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Nick
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Yep - the base of the mill will be one solid block and the epoxy supposedly has 15 times more vibration dampening ability than cast iron.
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Post Tue Jun 27, 2017 1:09 pm 
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