DFX file

[DPittman]

OK, I'm over my head here......

Most will think that I must be either a 5 year old or a 105 year old (I'm about in between actually) because I don't use, or know a damn thing about CAD programs.

I am trying to get a life size print of an internal gear I want to attempt to make on my lathe and I need to grind a single point tool to match the drawing of the gear.

It was recommended to me to use a GearDFX to make the drawing, which I did and that was super simple! I understand that I then have to use something like Fusion 360 to print it out? I went ahead and downloaded the trial version of Fusion 360 but then its all down hill for me from there! I don't know how to get the file to show up properly and then print????

Is there an easy way to take a DFX file and print it off without having CAD know how? Like convert the dfx file to a pdf ?????

 

[trlvn]

Can you attach the dfx file? One of us can surely print to pdf and send it back to you.

Craig

 

[DPittman]

Can you attach the dfx file? One of us can surely print to pdf and send it back to you.

Craig

AAAARRGHH! I can't even do that?! I went to attach the file and I get a message saying "The uploaded file does not have an allowed extension"

 

[DPittman]

And the file is a dXf not dFX as I stated.

 

[PeterT]

There should be a few folks on the forum who can help including me. Craig is first in line LOL. I don't run Fusion but I'm pretty sure the workflow might be like other CAD programs. DXF stands for Drawing eXchange Format. It came out of the 2D Autocad days but is very common for both CAD & feeding 2D devices. Everything from laser cutters to vinyl lettering cutters (throuh their import software). But DXF is is not really a standalone thing that can typically be printed directly. Kind of like .xls is not really a standalone spreadsheet file that can be printed directly (you need Excel). PDF stands for Portable Document Format. It is a very universal format that ll kinds of text/graphic programs can understand.

So in a 2D program
- load the DXF file (shows up on the screen all is good)
- set up the print job (specify scale, paper size, portait/landscape format.. etc)
- save as PDF (if it has that feature). Now its a standalone PDF file you can email or print or whatever
- if in cannot 'save as PDF' it should be able to Print as in hardcopy to your printer. But rather than selecting your printer, you select a PDF (kind of like as though its a device). Sometimes this comes along with your printer driver software & shows up as a selectable option. Otherwise there are aftermarket freeware PDF apps.

In a 3D program like Fusion (guessing a bit here) there are a few more things
- the DXF file is only a 2D outline at this point. Think of it as lines on a paper. Its not a 3D object yet. So it could be that within Fusion you need to extrude this outline to the gear width, now its a solid object. Then you can make a drawing (print file if you prefer) of this solid object and select the view that shows the gear in plan form. This probably sounds like clunky bunch of steps from your perspective but you have to remember a 3D object maybe be very complicated so typically you may require printing many different views (top, bot, left, right, underneath, perspective .... different scale, section views...) So TOP is just one of many views it is capable of.

If all you are doing is 2D there are probably lots of packages out there. But I'd say give Fusion a go, it will pay dividends later. Learning it by trial & error is not going to happen though. Get access to some video tutorial going starting from ground zero. It will come together.

 

[trlvn]

AAAARRGHH! I can't even do that?! I went to attach the file and I get a message saying "The uploaded file does not have an allowed extension"

You should be able to upload your drawing in ".zip" format. If you're not sure how to compress the .dxf file into a .zip file, tell us which operating system and version you are using and we should be able to help you.

Craig

 

[DPittman]

Ok Sorry for the delay. I was busy shoveling out from one heck of a snow storm down here.... I am sort of jealous of you guys with a snow blower. Most years we can get by just fine without one but this year I could have used one at least 4 times already!

I have zipped the dfx file and will try to attach. I then need to find some time attempting to learn the most basic things about Fusion 360.
I appreciate the help folks!

 

[YYCHM]

Here you go. Relatively easy using QCAD.

 

[DPittman]

Here you go. Relatively easy using QCAD.

That was fast!!!

Only problem is it appears the image was blown up to fill the page. What I'm trying to do is get a true life size of the gear so I can "copy" the gear spacing profile.

I want to grind a cutter point to match the drawing. However I am thinking it is going to be very hard because of the small size (module 0.5) the internal gear is only 1.5" inside diameter. This is the only way I can think of to attempt to get the right tool tip profile.

 

[YYCHM]

Ok..... how does on make that gear on a lathe? Are you broaching the teeth and using the lathe as an indexer?

Can you not scale the PDF to print the appropriate ID?

 

[DPittman]

Ok..... how does on make that gear on a lathe? Are you broaching the teeth and using the lathe as an indexer?

Exactly!



Can you not scale the PDF to print the appropriate ID?

I don't know what size/scale that drawing was or else yes, then I think I could just print to xx% scale. Am I missing something?

 

[YYCHM]

I don't know what size/scale that drawing was or else yes, then I think I could just print to xx% scale. Am I missing something?

Probably not. Try this one.

 

[DPittman]

Don't work at it too hard, I might be dreaming anyhow. I'm trying to use an external gear as the master copy and I can see it looks very difficult task to get precision on such a small scale

 

[PeterT]

I imagine that is going to be challenging if I understand correctly. A module number of 0.5 (which is mm) is equivalent to ~ 0.020 inch IMP units nominal tooth spacing'. That means basically your tooth form tool is going to be about that wide & the crown shaped to some pseudo-involute form. Even if the paper copy was digitally perfect (which it wont be) that will still be a bugger to grind the tool, hold it up to the outline, rinse & repeat. Is that what you mean?

I think printer resolution DPI means linear dots-per-inch. So say 600 DPI = 1/600=0.002" stair step jaggies. That is .002/.020= 10% of the tooth form you are trying to adhere to. So you would have to have higher resolution capability & that doesn't mean the printer is perfect, it also has aspect ratio distortion. There are ways of making gear cutters to yield the involute tooth form using round blanks, but these are cutters for spur gears, teeth on the outside. I think internal (ring gear) tooth form is different which is why guys have a tough time making them. I've heard some people fake it & use the spur tooth form as a broach. I'm not sure how accurate it is, but I guess this depends on what you are making & how much tolerance you can accept. Small stuff is hard!

I take it you have exhausted trying to find a commercial one or they are big $$?

 

[YYCHM]

Is 3D printed an option? I was surprised when RobinHood told me synthetic was a viable option for my delinquent feed gear.

 

[DPittman]

I've heard some people fake it & use the spur tooth form as a broach. I'm not sure how accurate it is, but I guess this depends on what you are making & how much tolerance you can accept. Small stuff is hard!

Yes I wondered about that. I might have to try the same. I'm wanting to broach a brass internal gear so maybe if I cut a few external teeth in steel that would work well enough in the brass.

I take it you have exhausted trying to find a commercial one or they are big $$?

Well I haven't come across them but I read don't know really where to look. I know gear hobs are available but what I want is a single point cutter. I imagine that would not be a commercially available thing?

 

[DPittman]

Is 3D printed an option? I was surprised when RobinHood told me synthetic was a viable option for my delinquent feed gear.

Oh probably. I happened to come across the external 36 tooth gear I made myself and it was available for ridiculously cheap but then I would have missed all the fun and learning of how to make my own! I'm kind of thinking the same for the the internal gear. I might have to eventually "jump ship" though. LOL.

 

[DPittman]

Yup that one worked just like I was thinking, but now I can see the task is going to be damn near impossible. Thanks for the work.

Probably not. Try this one.

 

[PeterT]

No, I don't think you are going to find a single point broaching type cutter in any tool catalog. I found the link that discusses the 4 required correction factors that must be applied to a regular involute (external or spur gear) shape to avoid interference. So this must be factored into commercial hobs when they make them. I cant think of a good, systematic way to make a hard, single point broach. If you find a link let us know. I've heard some people who have computed the corrected, exact tool path outline have has them wire EDM'd but that cant be kind to a mans wallet.

Madler (Germany) has module 0.5 internal gears in brass, 20-deg PA, but no 72. The common mod-5 teeth count seem to be 50,60, 70,90,100
https://www.maedler.de/product/1643/1618/260/innenzahnkraenze-messing-modul-05

KHK USA? steel 60,80,100 teeth
https://khkgears.net/pdf/si.pdf

Just curious, are you contemplating a planetary gear assembly? Because now there are added constraints in that the clusters must have coincidental pitch diameters which greatly limits the internal gear tooth count that will work. Is 72 a hard number for some specific reason?

 

[DPittman]

Well it's looking more and more like a poorly dreamt up "plan" on my part.
The gears were to be for a "Elmers #5 geared engine"

The plans call for 48dp gears but I could get a 0.5 module involute cutter from china cheap so - figured I would adapt accordingly. The 0.5 module gears would give me very close overall gear dimensions to the plan specified 48dp ones.

I don't have a milling machine but I can cut external gears on my lathe and hoped to broach an internal one using a newly made slotting attachment for my lathe.

Using a single point broach cutter was in my opinion "appropriate technology" for me, but I didn't realize how hard it would be to get a prison ground bit that tiny!

I know it's a crap shot, but I have now pulled out my stereoscope (microscope) to see if I can't eventually bumble grind a point that fits the needed profile. Those are tiny teeth!