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https://www.drdflo.com/pages/Projects/CNC-Mill.html
What's the best cnc conversion I can get that can cnc out precision parts really accurately?
I'm new to cnc machines and manual mills so I would like to be able to learn as I go too.
I want high quality metal parts
How good is the project I linked? Are there better ones?
Define precision and accuracy in the context of your needs.
I was wanting it to do extreme tolerances for moving parts that will rub together.Quote:
Originally Posted by Jim Dawson
That tells me nothing. Will the machine make a flat surface? Yes, depending on the skill of the user. Are you going to do NASA quality work on it, maybe not so much. Adequate for most applications? Probably.Quote:
Originally Posted by Pullarius
Quote:
Originally Posted by Jim Dawson
I wasn't wanting NASA level just professional quality. I dont know enough about CNCs to know what I need to make what i want. I was wanting to make gun parts and idk if that's allowed on this forum or not. I can legally make gun parts for myself in my country and state.
I was wanting to make top quality gun parts not cheap parts that malfunction and jam.
I've shot guns my whole life just never made my own from individual parts or even put together a parts kit.
Hello.
Some advise notes for what they could be worth.
As Jim Dawson says you must first define the characteristics of the finished products you are planning to manufacture according to their final use and then select the proper machine to achieve that quality.
In a company I worked for we manufactured from pins to airplanes. That gives you a broad selection of machines. For some parts in our airplane division accuracy had to be within 0.00001" and that was for crop dusting planes. For zippers and snap fasteners tolerance is normally kept within 0.0005".
Another important factor to consider is the speed of the machine. That is how many pieces per hour you can afford to manufacture to keep your costs down an yet have the profitability that you want.
Remember that as you increase accuracy speed is normally decreased. In that case you may need to switch from stepper driven systems to servo driven systems. Of course the price of these latter machines or retrofit kits is higher than that of the formers.
To make my point please watch the following videos.
https://www.youtube.com/watch?v=ErNjNtC60As
https://www.youtube.com/watch?v=7MuOlVDJPg0
Both machines manufacture the same products. The first one is driven by steppers. The second is driven by servos.
By listening to the machines you can easily notice that the latter runs faster than the first. In fact nowadays it is running slightly faster than twice.
In this particular configurations the price of the latter is nearly twice of the first. It would have cost some 20% less if the configuration had been exactly the same but in this latter system the owner required some additional function but in any case that gives you the idea.
And it not only depends on what you want. If the owner of the first machine had wanted a servo system to increase its productivity it would simply would not have been possible due to the mechanical design of his machine. Using servos on it would result in a waste of resources as it was impossible to fully take advantage of them as the machine would not hold onto the extra stresses of high speed operation.
So you see there are a number of factors you need to consider before buying a machine and then some. You will have to search for different machines that can produce what you now want but you have to take also a number of considerations like future upgrades, availability of spare parts, availability of service, etc.
If possible try to get advice from professionals in your areas. Maybe you can pay a visit to actual workshops to take a look at what they do and what equipment they are using.
It may also be possible that you get advice in this very forum from people like Jim as they are more related to the field. Or it might even be possible that some member is nearby you.
One possible recommendation would be to take your time so that you select the best possible machine for your needs and your budget. Either being a hobby or a professional issue always think of it as an investment, not as an expense.
One last advise thay may not apply to you but I always tell my customers when facing the acquisiton of used machinery. They have to think on why a particular machine is for sale. Was it that the owner renewed his equipment?
It´s very common in the industry that when a machine starts to give problems and spare parts start to become scarce they decide to sell them while they can still sell them as machines. They also do that when their operating costs start rising above certain level.
I sincerely hope this reflections help you take the best possible decision.
Regards.
Then the answer is yes. A lot of firearm parts are made on machines just like that by hobby users. And yes, firearm discussions are allowed.
Thanks for the great reply I was planning on doing small scale so I dont think I need speed just accuracy and precision parts. I'm not sure I'm saying the correct terminology thoQuote:
Originally Posted by BBMNet
What quality of gun parts would a diy cnc machine make? And do you have a machine youd suggest for making the bulk of the exspensive parts like receivers and idk if a bolt is millable or not tho.Quote:
Originally Posted by Jim Dawson
That machine would make all of the receiver, any mill work needed on the bolt, and anything else required. A lot of lowers are made on similar machines. Your not going to make barrels, or do any chambering on it of course.
Thanks I'll look into that machine or others that are reliable I liked the oiler on it.Quote:
Originally Posted by Jim Dawson
Matt (PM) sells good machines with super support.Quote:
Originally Posted by Pullarius
Are you saying you sent a pm? I dont know how to set my settings on this website so I can see them.Quote:
Originally Posted by Jim Dawson
Does he have a website?
No, that machine you linked to is a PM25 (Precision Matthews), with an added CNC kit. Matt is the owner. https://www.precisionmatthews.com/shop/pm-25mv/Quote:
Originally Posted by Pullarius
Which of his would you suggest for a beginner trying to get into gunsmithing? And what all attachments?Quote:
Originally Posted by Jim Dawson
Sorry to bombard you with questions I'm just not experienced with metal working.
Oh man, you ask hard questions :) The list is endless.
You need:
Tool bits; endmills, drill bits, center or spotting drills, countersinks.
Tool holding; collets, drill chuck, maybe endmill holders
Work Holding; vice, clamp kit
Measuring instruments; mics 0 to 3'', digital caliper 6'', dial indicator 0.001'' reading, dial test indicator 0.0005'' reading, edge finder
Other tools; files, deburring tool
That should be enough to get you started.
Hello.
A note on retrofitting mechanical machines. Any type for that matter. Mills, lathes, quilters, drills. You name it. By mechanical I mean machines that have never had any control other than manually turned handles or cam drives.
Since retrofitting usually requires that you substitute the standard transmissions with some high precision ballscrews or gears you can set your precision to whatever you want. Even if you don´t replace those transmissions and just motorize their handles you are the one who decides what precision you are going to give to your machine at issue.
Note: the main reason to replace a transmission is the free play that standard transmissions have. That would introduce position errors distorting the geometries being machined.
Please take a look at the posted pictures. the gear and screw shown have a ratio of 10/1. That is that the rolls driven by this speed reducer rotate at 1/10 the speed of the motor. Disregarding the microstepping switches on the drives and assuming a 200 steps per revolution motor the output shaft would require 2000 steps of the motor to complete one revolution. That is 10 full revolutions of the motor.
If I wanted to have better precision I could replace those gear and screw by a pair having a 20/1 ratio. In that case 4000 motor steps would be required to complete one revolution on the output.
As that action would reduce the speed to half I would also have to double the frecuency of pulses to the motor so that the RPMs are kept constant.
All that is possible within certain limits as steppers lose torque as they are run faster. That´s why in some cases you switch to servos. They can be run faster without so much torque reduction.
I hope that this comments clarify the fact that it is mainly the design of the retrofit system that sets the precision, not the machine. Just make sure your selected machine is rigid enough and doesn´t have to much free play in its rails and guides.
Regards.
Wow that's a lot of needed parts to it. Will some machines come with that or is that all extra?
So I guess after reading both your answers my next question is.
Is it better to buy a cnc conversion kit as a beginner looking for a high quality cnc machine or is pure diy better?
I would look for a kit something like this. (Disclaimer: this is not a suggestion, but is only an example) https://procutcnc.com/product/pm25mv...onversion-kit/
This particular kit does not include the motors, but those are readily available, as are the other electronics needed.
Edit: I have no idea what BBMNet is posting pictures of, but it is not a CNC mill.
Oh ok thanks I'll look into mills and then a cnc conversion kit for the one I want.
I saw a pneumatic drill bit loader onto the mills is that an upgrade or something you can retrofit onto one that has the twist on I dont want to twist them all on and off every time I have to switch bits.
And I'm guessing self loading drill bits are exspensive for diy so I probably wont go that route.
I think what you are talking about is a power drawbar. You could make one, there are all kinds of videos and posts about them.
Thanks you have been very helpful :)Quote:
Originally Posted by Jim Dawson
My pleasure :)
Hello again.Quote:
Originally Posted by Pullarius
It all depends on your needs, budget and of course what you want to manufacture.
My current job is retrofitting both "dead" cnc machines and converting mechanical machines. Please remember my definition for "mechanical" machines.
Since retrofitting or conversion usually costs a fraction of a new or even some used cnc machines some of my customers have us work on their machines so that they can start offering new products to their customers and save money to eventually buy newer machines.
I must also say that in some cases, in particular with originally CNC machines, after they are retrofitted they nearly reach the production levels of a brand new machine so it´s usually not appealing to buy a new one and so they stick with their old one.
In this latter case they know they can have local, relatively fast and less expensive service should they ever need it.
The turning point to keep their old machine or buy a new one is the mechanical condition of their machines. In some cases we also do a full overhaul changing worn parts like bearings, ballscrews, linear guides and whatever is necessary. In this case the time factor is also very important. It´s of no use if I can have a machine work as a new one if it takes me a year to complete.
And yet some customers buy what I would consider real piles of junk and still have us work on them. One such case is one Gribetz quilter shown in one of the videos I uploaded to YOUTUBE. It took us nearly 5 months to complete. It´s running at about 85% of a brand new machine but according to its owner the total cost including our time and service was still less than half than the new one. He could afford such time as he has other machines in his factory.
After all this speech and regarding your question, I would first start asking what your intended products are. If you can give me some insight, maybe I can help you to first decide on going DIY or buying a commercial machine. From then on it would be a matter of analysing options to find what could probably be best for you.
I´m sure that in any case other members can also help you decide (or get more confused) but it´s possible to get things done. The most important thing to my understanding would be to avoid you spending your money on something that will not service you as you need.
A personal note on advise from salesmen. While there are a number of very well trained people out there they are still salesmen and for good of bad their intention is normally that of convincing you to buy their products. So take their advise with caution.
Regards.
Thanks I am wanting to do small scale high quality gunsmithing. I probably wont sell them unless I get good at it and get all the proper licenses.Quote:
Originally Posted by BBMNet
It probably will just be hobby level making guns I want that are not available any more or making guns that use existing gun designs but have an outer shell of a games gun to look like one from a video game.
Hello.Quote:
Originally Posted by Jim Dawson
Your are correct. They are chain quilters. I posted them to make my point in the fact that esencially it is possible to do about the same job using steppers or servos.
The first machine uses steppers while the second uses servos. The software is about the same but if you listen carefully you will notice that the second machine runs faster than the first.
That´s all about them.
You want to see a mill? Well, the most like machine is this.
https://www.youtube.com/watch?v=B6FiInwcxh8
Again the software is the same but in this case the graphic interface is activated. This is an analog servo driven machine.
My software was designed in modules. As such when we retrofit any given machine I just select the corresponding motor controller and that´s it.
As I mentioned before my software is not particularly appealing as the workscreens are very simple but I do not need any external motion controller. It is the PC that takes care of everything. In some machines even the logic controllers of some servos and VFD´s are emulated by software modules. Imagine a servo drive where all you can see are the power transistors linked to the PC via some OP-AMP and a couple of small signal transistors and a pair of optocouplers.
Regards.
Quote:
Originally Posted by BBMNet
Which is better for high quality low production?
Servos or steppers? I dont know anything about machining I just know it's very complex
Hello.
In my opinion the selection is mostly dependent upon the type of machine and the parts you intend to manufacture. While steppers offer lower cost implementation they cannot effectively be applied on all machines.
If you got to watch the videos showing the quilters the first one uses a stepper based system. Since the machine is a very light one while it would have been possible to use servos they would have been a waste as they could not have been configured to run faster then about half the speed they could deliver. Steppers were the right choice for this machine. 1600 oz-in Nema 34 motors were selected. They are small with power enough to move this machine in open loop mode. No lost steps during operation.
Regarding the second quilter we dealt with an originally CNC machine. It´s a rather heavy rigid machine, While steppers could have been used here the selection would have involved large sized motors and still risk lost steps. The right choice was to use servos. After checking on the machine´s original motors we selected newer equivalents. This particular machine arrived as little more than a pile of junk. Rusted, some parts bent or broken. Yet the owner wanted to give restoration a try. And we took the challenge. Fortunately we got it working. As a new car it had first to be run at a relatively low speed and that was 50% faster than the machine in the first video. Nowadays it´s running slightly faster than twice that machine and it still has faster configurations to go.
One personal note on closed loop stepper systems. While they operationally pose an intermediate choice in between of steppers and servos, at least here in México the price even if you import them directly is too close to servo equivalents so it´s better to go with servos. And of course they give you the possibility of higher resolution and repeatability.
As It was mentioned before you can get advise from some salesmen but take their advise with caution as they will always try to convince you on buying their hopefully best option to solve your manufacturing needs but of course none will tell you that someone else´s machine is cheaper or better for your needs.
I´m trying to contact some of my former mechanics who may have better ideas regarding this subject of yours about doing some gunsmithing. I will post back as soon as I get some answer. It will probably be next week as I´m more likely to find them on weekend.
Regards.
Servos are always better than steppers in any machine tool. Today there isn't a huge price difference between quality steppers/drives vs. servos/drives. Servos are a bit more of course, but the advantages (speed, accuracy) are well worth the cost difference.Quote:
Originally Posted by Pullarius
Thanks for the great reply guys. Y'all have been very helpful with this. I still feel like I'm over my head but I have watched some videos and with y'all's help and the videos I'm learning a lot.
Servos for sure you won't find any CNC machining centers that use steppers, even quality hobby machines use servosQuote:
Originally Posted by Pullarius
I know nothing of firearms or gun smithing so I'll ask an uninformed question. Does this type of work require simultaneous movement in 2 or more axis ? A manual mill with DRO can do precision work but if the work is complex the accessories needed will run you broke.
I don't know either can a diy cnc machine of a manual mill not do that?Quote:
Originally Posted by cyclestart
Consider that people have been building firearms for about 1000 years, since the Chinese invented gunpowder. It has been a progression from a dirt floor gunsmith shop and crude hand tools, to modern CNC equipment. Looking back about 100 years, all firearms were built on manual machines. The success of the outcome is really dependant on the skill of the gunsmith. This is the case whether using hand tools or CNC equipment.
Hello.
Let me elucidate on cyclestart´s comment.
Most processes can be done manually. In fact they were originally done that way. Be it gunsmithing, furniture or even art.
The idea behind automating any process be it a CNC or any industrial process for that matter is to minimize safety risks on the operators due mainly to the boredom of performing repetitive tasks and to guarantee that the manufactured parts are as equal as possible to one another so that assembly can be easier.
To make my point on the latter just remember that the Secesion War was won with the help of automated gunsmithing that allowed for mass production of guns and rifles and that all parts were interchangeable.
I can´t tell about prices nowadays but if you´re planning on investing on DRO (Digital Read Out) units I must say that there a number of low cost CNC controllers that go for less than a set of DRO´s. I wouldn´t recommend them though as to my judgement they are difficult to program but I have not really gone through learning about their systems as I have my own but in any case I think they are worth a look.
There is some post in this forum about those controllers that might also be worth looking for.
Regards.
PS: cyclestart´s question remains valid. How many axes do you think would be needed synchronized at any one time. That´s a question one of my former mechanics asked me. As requested before please confirm if possible the steel grades you will be using. According to him it should be 4140, the very grade we used the most for our own machines.
A low cost DRO should be at least as accurate as low-end Chinese digital calipers. I'll let the reader decide how to interpret that statement ;)
Hello.
The following link takes you to the web page of a commercial CNC machine that I think might be what you are looking for. In any case I think it´s worth looking at.
https://www.kickstarter.com/projects...nd-capable-cnc
I suggest you talk to these guys and tell them about your intended application.
It´s a small machine capable of working on steel. MACH 3 appears to be its control software, so it would be possible to get lots of help whether in this forum or others besides the support from the manufacturer.
Regards.
As a life long Machinist and former Federal Firearms manufacturer (type 07 FFL) I will tell you that to succeed this will require a multi-year commitment. It could be 2 years before you make your first gun part.
First - Check your local community colleges and trade schools to see if they have a machinist or gunsmith training classes. Get into a class and start turning handles... For your own shop, do you have enough space with good power? All the little support tooling takes up alot of space and needs to be well organized so that you can find the tooling you need when you need it. Think about 1 full height rollaway tool box per machine. Another full box ( or dozen ) for your inspection gear, mics, calipers, thread gages, pin gages, loupes, reference tables, charts, books etc.
Storage space for your raw stock.
As you learn how to use someone elses machines you can get a better idea of what you will want/need in your own shop. Be honest with yourself about "want/need". I want a HMC with a 50+ tool ATC and 16 pallet magazine, But a plain 30 tool VMC w/o pallet can make the same parts - only less per shift.