FS: D|Focus - The $100 Follow Focus

[BWC]

I doubt custom machined gears would be inexpensive. Molded gears are cheaper but the cost to get a custom mold built would be out of the question for the quantity I am building.

Excellent BWC, thanks! The idea of making a rubber mold for gears did cross my mind, but I dismissed it thinking that it would be difficult to get it right. This post makes me think other wise.

Ok guys I think I can see that cost effective lens gears should be my next priority. I will use the profits from the first batch of D|Focuses to work towards this.

A combination of the two will serve you well. If, for each gear you need in your FF system, you get one custom machined, they are your gears to copy. You can make a mold of each of them (and likely many other parts) and copy them to your heart's content. The price of the custom machined gears will be a one time investment.

Also, you can buy casting resin in much larger quantities than Hobbycast sells it in. I expect that you will be able to sell a lot of these follow focus units at the price you are asking. As such, I would suggest buying a five gallon drum of each part. That will bring your cost per piece down to pennies.

I have been looking for five gallon drums of each part of the silicone rubber, but have not found it yet. I am sure it is out there. For you, I would suggest making a mold that is like a muffin baking sheet. You know, twelve spots for making a dozen in one batch? I would make two or three of those. That way, one run could last you a while and save you a lot of turnaround time.

Once you get good at casting molds, you should be able to use the technique to make a wheel that will accept a whip. I would suggest buying a commercially available whip, casting a mold of your current wheel (Mold A), then creating a circular mold box about half the diameter of your wheel.

Drill a 1" hole in a piece of plywood and put the whip through the hole. While holding the plywood, put the tip of the whip against the table and measure the distance between the bottom of the plywood and the table. Add 1/4" and cut two pieces of 2x4 to this length. Screw the plywood to the 2x4 to create a spacing jig.

In the circular mold box, mark the exact center. Next place the spacing jig above the circular mold and allign the male part of the whip with the center of the circular mold. Cast a mold of this (Mold B).

Place Mold B inside Mold A and center it. Rather than filling it with casting resin, you would fill it with moulding rubber to create Mold C. Fill Mold C with casting resing, let it set and remove the mold. You will now have a replica of the face of your wheel with a female whip attachment.

Cast a mold of the other side of your wheel, fill it with casting resin and remove the mold. Using a bandsaw, make your replica of the bottom of your wheel 1/4" thick. Using a thin layer of your casting resin, laminate this to the bottom of the new wheel face you have made. Sand the join to make it uniform. Create a new casting box, make a mold of this, and you can make as many whip-ready wheels as you like.

[designbydave]

Thanks for the advice BWC. I do have some experience with molding (mostly composite materials, fiberglass, carbon fiber etc.) I just haven't done any rubber molds like this.

I am looking into all of this.

[BWC]

No problem. It looks like most of yur parts could be molded; not just the gears. You could really find yourself in a position where, even at this price, your proffit margin is very steep. I think you will do well with this even as it is. Get to where this thing will accept a whip and it comes with a lens gear without the price going too much higher and you will be busier than you ever imagines you could be. Best of luck.

[previdman]

Nice idea. Nice video. What concerns me from the demo video is it seems a little overpowered...meaning the pull appears very quick rack to rack.

On the bushes shot for example, you blow right past mid-field going from distant to near. Since there are no stops or marking plate, is this unit capable of a more controlled pull?

Using industry standard pitch I would imagine it's as sensitive as any other 35mm FF but your demo video doesn't show that amount of fine control.

[designbydave]

Oh I just remembered this:

http://store.zacuto.com/zip-gear-replacement.html

Only $12 but you would have to figure a way to mount it. Don't know for sure if its 32 pitch. Might want to email them to be sure before ordering.

[Rumple]

That zacuto replacement gearing is 32p, i emailed them.

[paramon]

Hey Dave,
when/if improved model ( crank, whip, disk, maybe all aluminum anodized) will be available, will be there any upgrade options for previous customers?
thank you;

[designbydave]

Hey Dave,
when/if improved model ( crank, whip, disk, maybe all aluminum anodized) will be available, will be there any upgrade options for previous customers?
thank you;

This is the plan. I think I have a pretty modular base unit here that lends it's slef well to upgrading/customizing/modifying.

[Rumple]

Good stuff. Just getting my cash together to purchase.
Any word on the shrigg test?

[David]

Any plan on selling those rail blocks separately? Are they aluminum or delrin?
Thanks

[designbydave]

Any word on the shrigg test?

No test with the Shrigg but it is not necessary. The height of the IndiRails that I have is the same as the Shrigg. That is what I was worrying about not working.

[designbydave]

Any plan on selling those rail blocks separately? Are they aluminum or delrin?
Thanks

Yes!

I think they could be a very useful DIY item. They are made of Delrin which is a very pleasant material to work with. Its a very hard plastic but is not brittle. It machines very well without melting like most other plastics will. You can drill, tap, cut, sand it etc...

[previdman]

OK. Since you didn't bother answering my earlier question, here it is again: Your demo only shows quick pulls from far/near/far (rack to rack.)

Since there are no stops or marking plate in the design and by your own admission, the gearing is a bit "loose," is this unit capable of a more controlled, finite pull? Close/mid/far or any combination thereof.

I believe that's a fair and rather important question which should be answered.

[dc7ks]

would it be possible for you to make some sort of mounting situation for the maplin gear?

[designbydave]

OK. Since you didn't bother answering my earlier question, here it is again: Your demo only shows quick pulls from far/near/far (rack to rack.)

Since there are no stops or marking plate in the design and by your own admission, the gearing is a bit "loose," is this unit capable of a more controlled, finite pull? Close/mid/far or any combination thereof.

I believe that's a fair and rather important question which should be answered.

Without stops or markings you have to focus using the image your LCD. This makes it more difficult to pull off a rehearsed focus pull (directly from object A to object B) especially if you want to focus quickly. There is a good DIY sense in this community and I am sure most people will find a way to pull the focus they need. I remember seeing an interview with a pro AC and said he never uses a marking plate. If anything he would mark the lens its self.

As far as the loose gearing; it is loose in the sense that there is just a few degrees of "play" in the knob. You can absolutely get very precise movement from your lenses focus ring, you just have to be aware that the knob will rotate just a bit before the lens ring does.

Hope that answers your question. Some times its hard to explain thing in writing (especially for my lack of literary expertise.) If you would like, give me a call on skype (link on the website) and I would be happy to discuss this further with you.

Thanks for the interest!

[designbydave]

would it be possible for you to make some sort of mounting situation for the maplin gear?

I can make just about anything, but I'm not sure what you are referring to. Are you talking about that right angle gearbox sold by Maplin?

[Rumple]

A bevelled gearbox is what I think he means...

I was interested in this too, as they are contained rather than your open gear styled gearing.

I didnt ask though, as I feared being branded a trouble maker.

[designbydave]

A bevelled gearbox is what I think he means...

I was interested in this too, as they are contained rather than your open gear styled gearing.

I didnt ask though, as I feared being branded a trouble maker.

Anyone have the dimensions of the mounting holes?

[dc7ks]

Yes that's what I'm talking about. For the longest time ever, I've been looking for a way to mount my follow focus. I was wondering if you could help me out with the mounting solution.

[dc7ks]

Anyone have the dimensions of the mounting holes?

I'm actually quite close to rancho. We could meet up if that would be convenient.

I'll try to put up the dimensions tonight.

[dminor]

Here's a link to the dimensions:

http://images.maplin.co.uk/full/n16bq_diagram.jpg

[designbydave]

I'm actually quite close to rancho. We could meet up if that would be convenient.

I'll try to put up the dimensions tonight.

Sure, come on by the shop in Upland when I'm there. Shoot me an email and we can work out a time.

[Unhollywood]

Sorry if this has been answered but:

Just to confirm the dfocus will work with the Shrigg?

and

Where can I get that lens gear?

[designbydave]

Sorry if this has been answered but:

Just to confirm the dfocus will work with the Shrigg?

and

Where can I get that lens gear?

Yes it will work with the Shrigg. I have not tested it myself but the height of the rails on my IndiRailsPro are set to the same as the Shrigg.

RedrockMicro sells the lens gear in the pictures. They are $63.50. Check the FAQ on the website for the link (sorry I can't post it here, no copy/paste on the iPhone, yet)

[dminor]

RedrockMicro sells the lens gear in the pictures. They are $63.50. Check the FAQ on the website for the link (sorry I can't post it here, no copy/paste on the iPhone, yet)

Just for clarification, the RedRockMicro lens gear most of us with 35mm DOF adapters should get would be "A"? Correct?