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Yes it was! I have FreeCAD 0.20, and it was an option on the 'export' menu!
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Erich's Benchtop Gear Hobber Project
- Thread starter ErichKeane
- Start date
- Joined
- Dec 3, 2014
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- 500
The hobber looks pretty nice! The plans are 5/10, but the castings are beautiful. I'd suggest getting it now so you can follow along with my build
If you can convince a few others, I could talk Gary into a group buy.
I'm late to the party, but I have been eyeing the hobber castings for years since I make etching presses with gear trains I keep making from scratch the hard way.
I also want the Quorn, UPT and die filer castings.. so I could basically do my own group buy... is there a forum for organizing such things?
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If you get in touch with Gary, I'm sure he could make you a deal directly! @vtcnc started a thread for a group buy at one point I thought, but I can't seem to find it. I don't know how much interest there was, but I'm sure if you're wanting that many things you can start a landslide
- Joined
- Dec 3, 2014
- Messages
- 500
If you get in touch with Gary, I'm sure he could make you a deal directly! @vtcnc started a thread for a group buy at one point I thought, but I can't seem to find it. I don't know how much interest there was, but I'm sure if you're wanting that many things you can start a landslide
If I stick to Southern Ontario there are plenty of hobby machinists so I potentially could put something together. But I fear that i'd still only get a couple of people interested.
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- Aug 3, 2017
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Alright, well, I got busy yesterday and didn't post my update, so today is a double feature!
First, for these lead screw brackets, I flattened the outside to thickness:
Next, I found the center of the boss best I could, since the rest of the measurements are based on that:
Finally, I drilled and reamed the lead screw hole, and used the DRO for the mounting holes. The crossfeed mount is a little different (since a quadrant attaches to it), so those holes also got countersunk. One gotcha: 2 of them are 400 thou between the mount holes and leadscrews, the other is .325. the plans say match drill, so this is where I had to pay attention!
After that, a test fit with these on the whole 3 axis setup:
I made a mandrel in the lathe with a 3/8" center to mount these so I could turn the OD. While drilling the end, I untwisted a #7 drill!
And here is the big one mounted on the mandrel. The OD mattered, and the depth didn't as much, but all are turned the same way. I used some bearing retainer loctite which stickied up just enough in 10 mins to hold the part still.
After doing all 3, here they are:
That was the end of yesterday!
Today, I needed to do the back feature, where a thrust bearing is sandwiched between the mount and the lead screw shoulder. I was able to get them setup easily enough in the 4 jaw, and bored it out, a bit more than .300 deep, and .800 around for clearance. The stack up is only .265, so there is plenty of depth.
After all 3;
Then, I started on another part: the feed quadrant, which holds gears to power the gear through the cutter. First operation was a but precarious, but I was able to flatten it well enough. My casting was a bit pretzelly, so in the end I end up about 40 thou too thin, but hopefully that doesn't cause problems.
Next, I flipped it over onto a fixture plate I made a while back, and milled the other side flat, moving clamps mid way through:
I used the boring head to get a tight fit on the lead screw mount:
Finally, drilled the clamp hole, used the cut off wheel to make it a clamp, then went back and clearance drilled the top, then tapped:
And, done, clamped onto the mating part:
And, that's it! All the castings in the "main tower", and all but 2 of the castings total! One of which I need a replacement, the other of which is another quadrant that attaches to that (so I have some adjustments I can use cutting it differently).
I'm on the fence whether I intend to drive the hour each way to pick up the replacement casting right away, or if I want to just start making the rest of the parts to assemble the main tower. What do you all think?
First, for these lead screw brackets, I flattened the outside to thickness:
Next, I found the center of the boss best I could, since the rest of the measurements are based on that:
Finally, I drilled and reamed the lead screw hole, and used the DRO for the mounting holes. The crossfeed mount is a little different (since a quadrant attaches to it), so those holes also got countersunk. One gotcha: 2 of them are 400 thou between the mount holes and leadscrews, the other is .325. the plans say match drill, so this is where I had to pay attention!
After that, a test fit with these on the whole 3 axis setup:
I made a mandrel in the lathe with a 3/8" center to mount these so I could turn the OD. While drilling the end, I untwisted a #7 drill!
And here is the big one mounted on the mandrel. The OD mattered, and the depth didn't as much, but all are turned the same way. I used some bearing retainer loctite which stickied up just enough in 10 mins to hold the part still.
After doing all 3, here they are:
That was the end of yesterday!
Today, I needed to do the back feature, where a thrust bearing is sandwiched between the mount and the lead screw shoulder. I was able to get them setup easily enough in the 4 jaw, and bored it out, a bit more than .300 deep, and .800 around for clearance. The stack up is only .265, so there is plenty of depth.
After all 3;
Then, I started on another part: the feed quadrant, which holds gears to power the gear through the cutter. First operation was a but precarious, but I was able to flatten it well enough. My casting was a bit pretzelly, so in the end I end up about 40 thou too thin, but hopefully that doesn't cause problems.
Next, I flipped it over onto a fixture plate I made a while back, and milled the other side flat, moving clamps mid way through:
I used the boring head to get a tight fit on the lead screw mount:
Finally, drilled the clamp hole, used the cut off wheel to make it a clamp, then went back and clearance drilled the top, then tapped:
And, done, clamped onto the mating part:
And, that's it! All the castings in the "main tower", and all but 2 of the castings total! One of which I need a replacement, the other of which is another quadrant that attaches to that (so I have some adjustments I can use cutting it differently).
I'm on the fence whether I intend to drive the hour each way to pick up the replacement casting right away, or if I want to just start making the rest of the parts to assemble the main tower. What do you all think?
- Joined
- Aug 3, 2017
- Messages
- 2,437
A little more work today! First, I bolted the L bracket to the frame, I had to widen one of the bolt holes in the bracket though, because my hand drilling wasn't accurate enough.
Next, I went to put the bottom slides dovetail in place, with the keystock in place. I discovered that I machined the keyslot wrong on the dovetailed piece! I put it in line with the bolt holes instead of about 63 thou further away.
I put this back on the mill and slotted the base bolt holes an additional 75 thou. They look a little oddly shaped because I didn't use the chamfer tool on it.
After that, it bolts on fine!
I actually then took it right off to put a little relief in all the slides, like this. The gib is held in place with the help of a pin, and this will let me be less accurate installing the pin to depth.
Speaking of gibs, time to make them! 1/2" by 1/8" brass cut into 6" pieces (quite a bit too long, but I'll cut them to size later), and a tilted mill head cleaned up the first side.
To get the other side, I milled a slightly thinner piece of aluminum with the same angle, then used it as a parallel. I ended up loctiting them together because I had a problem with them sliding.
Next, I had to drill the pin hole in the gib. After quite a few failed attempts, it took me too long to realize I already had a gib clamp! I ran the 3/16" endmill down the hole and cut it! You can see scars on this one from my failed attempts.
And that's it for today! I'll continue assembling the tower, making the parts needed to do so as I go!
Next, I went to put the bottom slides dovetail in place, with the keystock in place. I discovered that I machined the keyslot wrong on the dovetailed piece! I put it in line with the bolt holes instead of about 63 thou further away.
I put this back on the mill and slotted the base bolt holes an additional 75 thou. They look a little oddly shaped because I didn't use the chamfer tool on it.
After that, it bolts on fine!
I actually then took it right off to put a little relief in all the slides, like this. The gib is held in place with the help of a pin, and this will let me be less accurate installing the pin to depth.
Speaking of gibs, time to make them! 1/2" by 1/8" brass cut into 6" pieces (quite a bit too long, but I'll cut them to size later), and a tilted mill head cleaned up the first side.
To get the other side, I milled a slightly thinner piece of aluminum with the same angle, then used it as a parallel. I ended up loctiting them together because I had a problem with them sliding.
Next, I had to drill the pin hole in the gib. After quite a few failed attempts, it took me too long to realize I already had a gib clamp! I ran the 3/16" endmill down the hole and cut it! You can see scars on this one from my failed attempts.
And that's it for today! I'll continue assembling the tower, making the parts needed to do so as I go!
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- Aug 3, 2017
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- 2,437
Since my last post, I went and picked up a replacement for the casting I messed up.
AND, decided on my gear setup based on a hob I picked up on ebay:
16,20,24,25,28, 30,32,36,38,40,44,45,46,48,50,52,54,56,60,64,65,70,75, 80
From THERE, I did a bunch of programming (I'm a C++ Compiler engineer in my day job!) to try to figure out which gear sets I would need to get printed in order to be able to make 2 of each of those gears. I found a bit more than 400+ candidates and cut that list down as much as I could (limited valid gear trains by 'should mesh correctly' as well!), and have arbitrarily picked:
24 28 38 40 44 46 50 52
In doing the running, there are about 2.2 million combinations of 'gear trains' that result in one of the target gears (and are possible as best as I can tell!). I picked that set since it has sufficiently 'large' sets of gears that I think it can reach all the way across.
With those, I was able to come up with the attached document of 'how to get to all 24 gears' (and make a max of 2 of each!).
A gear-train has an 'input' gear, 2 'quadrant' gear-pairs, and an 'output' gear (plus there is a 20:1 reduction at the end!).
A Quadrant where both items of the 'pair' are the same are just a single-gear, and I represented them internally as a pair.
BUT 8 gears was the minimum I could find (though I THOUGHT there were some options for something like 16,16,16,20 when I was just getting started, but I cannot seem to reproduce that again!).
AND, decided on my gear setup based on a hob I picked up on ebay:
16,20,24,25,28, 30,32,36,38,40,44,45,46,48,50,52,54,56,60,64,65,70,75, 80
From THERE, I did a bunch of programming (I'm a C++ Compiler engineer in my day job!) to try to figure out which gear sets I would need to get printed in order to be able to make 2 of each of those gears. I found a bit more than 400+ candidates and cut that list down as much as I could (limited valid gear trains by 'should mesh correctly' as well!), and have arbitrarily picked:
24 28 38 40 44 46 50 52
In doing the running, there are about 2.2 million combinations of 'gear trains' that result in one of the target gears (and are possible as best as I can tell!). I picked that set since it has sufficiently 'large' sets of gears that I think it can reach all the way across.
With those, I was able to come up with the attached document of 'how to get to all 24 gears' (and make a max of 2 of each!).
A gear-train has an 'input' gear, 2 'quadrant' gear-pairs, and an 'output' gear (plus there is a 20:1 reduction at the end!).
A Quadrant where both items of the 'pair' are the same are just a single-gear, and I represented them internally as a pair.
BUT 8 gears was the minimum I could find (though I THOUGHT there were some options for something like 16,16,16,20 when I was just getting started, but I cannot seem to reproduce that again!).
- Joined
- Aug 3, 2017
- Messages
- 2,437
Ah, woops! I found my 'bug' I guess on the doing-it-with-only-4-starters. It seems it requires duplicates! At one point when programming (it is a VERY large search space!), I was trying to limit the search space and ended up disallowing duplicate 3d printed gears.
BUT there are a whole bunch that apparently let me get away with only 4 printed gears!
BUT there are a whole bunch that apparently let me get away with only 4 printed gears!
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- Aug 3, 2017
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So a few disorganized/all over the place sorta days, but not much to show of it.
I got all the lead screws cut, cleaned up, and turned down for a press fit extension. The extensions were then cut and drilled and press fit into place. 2 of the 3 got loctite, 1 I forgot.
I also got the replacement hob spindle housing casting, so today I did all the milling operations on that. I have to do the bores and area for the quadrant to mount, but I'm back to where I screwed it up last time.
I got all the lead screws cut, cleaned up, and turned down for a press fit extension. The extensions were then cut and drilled and press fit into place. 2 of the 3 got loctite, 1 I forgot.
I also got the replacement hob spindle housing casting, so today I did all the milling operations on that. I have to do the bores and area for the quadrant to mount, but I'm back to where I screwed it up last time.
Attachments
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- Aug 3, 2017
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A little more work done... I had a few discouraging days of not getting much done, and having to restart/etc, so I had a bit of a "reset" day. Additionally, a bigger angle plate came, which means I can do the hobber body, which means I can get the 4 jaw off the lathe
First, I decided to drill/tap my handles. Work holding was awful, but it worked. I got these from LMS, since the handles specified in the plans no longer exist.
The set screw is just an 8-32 I had left over from the gib screws, so I'll have to shorten them or buy shorter ones.
Next, I decided to continue working on the rest of the castings. I messed up this hob spindle housing last time, so I picked up a cheap shop made angle plate for this time.
I did some marking up, and got 4 holes drilled/tapped to use the mount holes to bolt it securely on the plate.
And here it is on the lathe. I had to bore the center to about 1.5":
Next, there is a second bore for the bearing on this side. Plans say slip fit, and I think I got it perfectly:
Finally, I had to cut the area for the quadrant clamp. Again, uneventful:
I have 2 things to do on the other side, which I might just do on the mill, but at least this setup is done.
First, I decided to drill/tap my handles. Work holding was awful, but it worked. I got these from LMS, since the handles specified in the plans no longer exist.
The set screw is just an 8-32 I had left over from the gib screws, so I'll have to shorten them or buy shorter ones.
Next, I decided to continue working on the rest of the castings. I messed up this hob spindle housing last time, so I picked up a cheap shop made angle plate for this time.
I did some marking up, and got 4 holes drilled/tapped to use the mount holes to bolt it securely on the plate.
And here it is on the lathe. I had to bore the center to about 1.5":
Next, there is a second bore for the bearing on this side. Plans say slip fit, and I think I got it perfectly:
Finally, I had to cut the area for the quadrant clamp. Again, uneventful:
I have 2 things to do on the other side, which I might just do on the mill, but at least this setup is done.