Laser Cutter or Welding Machine

Let me start this off by saying that I am somewhat of a novice when it comes to machining and am not very experienced. As a background, we already have a CNC mill that works decently with reasonable accuracy and speed.

My team has been discussing getting a laser cutter for a while to increase prototyping speed and (apparently) ease to use compared to a CNC. But now getting a laser welding machine has come into conversation, and our mentor says we can only get one. Another mentor is leaning towards laser welding, but I feel like it won’t be as useful as a laser cutter (again I’m not an expert so I turned to CD :slight_smile: ).

If people could give a recommendation, and maybe a recommendation on a specific product, I would be very happy.

Edit: Our budget is 5k USD.

Laser cutting is 10x more useful

Laser welds are cool, but the problem with welding is that it’s not serviceable in a competition. If it breaks, you don’t have a welder and you need to start adding L brackets and gussets. Which is why I do that from the start

That being said, a regular $3k laser isn’t going to cut metal. It’ll do wood and acrylic (the plastic you shouldn’t use). Its usefulness is basically prototyping things out of wood, as well as making signs and fundraising gadgets. Still, I feel it is more useful than a laser welder for FRC

I have access to both, and I only used the laser cutter last year, but not for any robot parts

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Wow, thanks for the quick reply! I never thought about it not being serviceable in competition.

Talking about an Apple and a Orange…

A laser cutter in the 5K range is going to cut MDF, wood, cardboard. and maybe plastic. Potentially great for iterative prototyping. Not so useful for comp bot parts.

I really don’t have any experience in laser welders. I suspect 5K is not enough. 5 grand will get you a great MIG/TIG setup that will weld Al and steel. Probably more versatile than a cheap laser welder. Keep in mind welding needs to be done either in a well ventilated area or with the proper vent hood. The arc will need to be shielded from other occupants.

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To be clear - that’s not to say welding isn’t useful. I just try and avoid it. I am not a great welder so my welds aren’t as strong

I’ve seen plenty of teams weld stuff. I know 67 had welds their 2022 climber and I’ve seen other teams with welds too that appear to work successfully

Laser welding is a little tricky to get right, but it does for sure produce clean good welds when done right

Laser welding doesn’t use any extra filler material (unless you have a special attachment). It just melts the two surfaces together. It is not as strong of a bond as a MIG or TIG weld, but it is smaller and cleaner

Also, please be careful. I have a few shirts with holes in it from laser welding. It will blind you if you’re not careful

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We had a fully welded aluminum elevator mechanism and intake in 2018. It looked cool and was rugged, but we would never do i again. Cracks started to form and we could not modify it much afterwards. The students wanted it welded, but learned afterwards the hardway it was not the best choice for future builds.

I don’t want to derail the post, but there are teams that cut polycarb on a laser cutter for robot parts. Please search CD for posts about the safety of doing so and make up your mind.

Fitup is super critical for laser welding.
Its really NOT a process for one off parts. Weld process developmemt takes time and test parts.

A laser cutter is quite useful. If you get your exhaust working really well (and consider adding mirror purges) polycarbonate lasers fine. Smoky. Spectrum has been doing it for years.

Welding wise, TIG is your go-to for FRC welding. A spool gun MIG will work on Aluminim too. Aluminum is a lot more tricky to weld than steel

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Oh, and you need some special design decisions for Aluminum welds.

The weld metal and the heat affected zone will both be weak. You need more reinforcement than for steel. AND, if you fit two parts together and run a weld down the joint, it will not penetrate into the mating faces at all, unless its SUPER clean and freshly scoured down.

Aluminum is tricky to weld. Poor weld prep and techniques will lead to cracks. It is not really a student activity unless your team has a mechanism outside of robot build to train welders. There are some places that welding is the best choice. We use outside resources for those. YMMV

Have you considered a CNC router? They are far more useful for FRC than laser cutters or welders. WCP sells the Omio X8 for $4k. It’s one of the most popular machines in FRC and will work with aluminum sheet/tubes, as well as any woods and plastics.

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If your team doesn’t want to go the CNC router route though, I’d recommend a laser cutter over any type of welder for sure. Just a lot more useful in the FRC space. Though many teams only use laser cutters for rapid prototyping but not final robot parts, Team 1771 actually builds a decent amount of their robot superstructures & mechanisms out of wood - when designed well, know it can be done! (@cmwilson13)

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I think you missed it, but I mentioned that our team already has a CNC.

You had mentioned a CNC mill in your original post.

Typically, a Mill has a smaller overall work volume (especially in the X and Y axis), and in general is more rigid than a router allowing it to hold better tolerances while machining harder materials.

A router on the other hand will often have a very large X and Y axis, allowing you to process larger flat sheets of material (often at the expense of rigidity).

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you did say a mill. we have a cnc mill that has sat untouched since 2011.

a router is MUCH easier and quicker to setup then a mill. we have a 100w laser a cnc mill and a 4x2 router and a manual lathe.

the router and manual lathe mke 99.9% of our parts we manufacture in house.

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My bad - I thought they were just two names for the same thing. We have a router.

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If you build your own field elements, a laser cutter is incredibly helpful for that as well. Massive time saver, and some things that just won’t perform the same if you try to hack them together with non-laser tools (such as circular holes in goals)

We had TIG and proffesional help over long hours of welding. Crack cam from impacts on yhe grabbing mechanism tha got his from impacts. Even good held wil only sustain so many hits.

I’d highly recommend a laser cutter. They’re significantly faster than a router or mill for prototyping, which is the point in time where speed is of the essence.
They’re also quite good for cutting Delrin which is not a bad plastic for FRC use. I don’t recommend polycarb unless you’re experienced, have excellent ventilation, and a fire extinguisher nearby, but it can be cut. I’ve just never had a good experience cutting it. If you put a lot of time and effort into learning how to run the laser well, you can get some really spectacular and accurate results. It’s second to none for sheer accuracy, especially on tight corners. A mill/router might be able to compete, but they can’t do the very fine details (like sharp inside corners) that a laser can, and routers in particular seem to have a tendency to wobble a bit on thicker/tougher materials.
A welder imo doesn’t offer too much utility for FRC unless it’s something that can easily be replaced and isn’t too difficult to weld, and even then I’d go with bolted joints over welded.

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Thanks to everyone for your responses and patience with me! We are going to buy a laser cutter after all :).

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