Drilling - fluting carriage

[Fred in NC]

Some progress has been made. The carriage has been made to .003 tolerances, which is about the thickness of a piece of typing paper. The reason it is being built to high precision is that unlike a bowl turner, we work with very small pieces of wood. I want to be able to use router and engraving bits in sizes from 1/64" and up.

The driving screw is ACME 1/2" X 10 TPI. The carriage length, from bracket to bracket is 12". Longitudinal movement will be about 8". The wood parts that you see in the pic are only temporary for testing. They are being replaced with metal.

I am working on the first tool holder and in/out mechanism, which will hold a regular Dremel (current model available at most stores). The plate that will sit on top of the sliders can be customized to hold different rotary tools.

The first prototype should be ready in about 2 weeks. If all goes well, I will probably have a few ready in about 4 weeks.

 

[JimGo]

WOW Fred, that's going to be SWEET! Much sturdier than anything I had envisioned.

 

[btboone]

Good job Fred. I assume you'll have the option to drive it with belts off the turning spindle. Slickness.

 

[Mudder]

I'm curious as to the reason you chose an acme screw? What do you do about the backlash?
Have you thought about a 3/8"-16 threaded rod? With the threaded rod one turn of the handle would be 1/16" and it is fairly easy to make an anti-backlash nut setup.

I love the design and would be interested in the finished product.

 

[Fred in NC]

Mudder, what backlash ? There is none! ACME backlash happens when you use a regular metal nut that does not fit properly. I am using a special self-lubricating nylon for the nut, and the threaded part is 1" long.

Common threaded rod was not designed for leadscrews, there is not enough thread depth to hold on to, and it will wear the nut a lot faster. ACME threads are kind of square. Also, ACME keeps the position a lot better once you set it, without any locking devices. I know a lot of people are using common threaded rod and plastics like Delrin, but I just don't like that combination. I did not use CRS either, the shafts are 1/2" drill rod which is precision ground.

I used 10 TPI because anything else would make the machine too expensive. As it is, a tap to cut threads in the nut is over $60 !!

There are a couple reasons for my building this unit:

First, I want one for myself, and I want some precision.

Second, it will be a guideline if anyone wants to build it to use with the indexing plate. As far as that goes, it can be made from wood, threaded rod and cold rolled steel rods from the hardware store.

Third, if there is enough interest, I can have a FEW built at one time. Machine shop time is very expensive, as most people are aware.

Thanks for your comments and observations. I can use all the help!!

 

[Paul in OKC]

It looks great, Fred. I agree with the acme thread for myself as well. One turn is .100, and it is a good deep thread. Anti backlash nuts are easy to make for regular all thread, and easier to come up with maybe for the one who wants to make their own, especially to make a lead screw if you are going to make the wooden set up.
Back lash for straight cuts is really a non-issue, you just pull the tool back and go back to the start of the cut. For spirals, no backlash would essential, but I would still pull the tool back to go to the beginning of the cut, just to avoid any play and have the tool cutting the same each pass. The regular Dremels are tight, but not as tight as a machine spindle.
Looking forward to seeing the finished product.

 

[Fred in NC]

Thank you, Paul. The newer Dremels are a lot better, but of course cannot compare with a precision machine spindle, which can cost in the thousands of $. The runout in the new Dremels is probably around .002" which is acceptable for drilling decorative holes and fluting, routing etc. As usual it is a matter of living with what we can afford.

To those who are not machinists, the nut for regular threaded rod should be made of a plastic that gives a little. Nylon is my favorite.

 

[PenWorks]

Fred, it looks like retirement is agreeing with you. You are coming out with a new product every month [] I can't wait to see the finish of this one. Could be something I could use.

 

[Fred in NC]

UGH ... retirement! Long awaited, not here yet. Probably a few more months of working at my regular job.

I will keep posting pics as the rest of the machine gets built.

 

[swm6500]

I will be interested in this Fred. I have been wondering what I could come up with to use with the index plate I got from you.

 

[Mudder]

Originally posted by Fred in NC
<br />Mudder, what backlash ? There is none! ACME backlash happens when you use a regular metal nut that does not fit properly. I am using a special self-lubricating nylon for the nut, and the threaded part is 1" long.

I see,

We make Acme lead screws and we also make threaded lead screws where I work. According to the federal screw thread standards an acme combination should have .006 backlash maximum. Of course the ASME standards are a little different and they have two. ASME standard B1.5 for regular acme and standard B1.8 or stub acme. Using materials like Delrin and Trucite and with specially ground taps you can eliminate backlash almost entirely

While it is true that common threaded rod was not intended for lead screws there are several varieties of ground rod that will serve as well as the Acme lead screw at a reduced cost.

Here are some fine places to look:

http://www.wmberg.com/prleadscrews.html

http://www.velmex.com/manual_lead_screws.html

http://www.efunda.com/storefront/product_detail.cfm?prod=150

I’m sorry; my question was borne from curiosity. I did not mean to imply that you did not know what you were doing or made an incorrect choice in material. I shall not bother you again with my questions.

 

[Fred in NC]

Mudder, I see you know your standards !! I sincerely appreciate your concerns and ideas. Sometimes it takes more than one head to arrive at a good solution, and you know your stuff very well.

I can assure that the combination I am using works real well. The material is used for bearings in DISK DRIVES !! The low coeficient of friction allows for a very tight fit.

One of my concerns is that I want to offer this carriage at a reasonable price. That has influenced my design. For example, a delrin antibacklash nut can well be used with common threaded rod. But, then you need a mounting for the nut, and a bunch of other parts. Using a single piece of material has eliminated a bunch of parts, and the result is a more solid assembly.

Common threaded rod will wear out a plastic nut in short order because it is very rough and has sharp edges. The thread on ACME rods is more solid, and has no sharp edges.

Time will tell. This will be throroughly tested !!

Thanks for the links.

 

[DCBluesman]

Thank heaven Fred and Mudder know what they're talking about. I got lost in the concept! []

 

[Fred in NC]

Lou, frankly I don't know much about what happens when I turn the ignition key in my car ... these new cars have so much stuff inside. However, I know it works, and I leave the fixing to a good mechanic. Same with everything else in life.

Remember, in these days of specialization, the are left foot doctors and right foot doctors. I have found that conveniently they usually have their offices next to each other []

 

[scalawagtoo]

When I saw that our AMT lathe had an indexing wheel I started thinking about how nice it would be to have a carriage for a dremel. However, it will be quite some time before I can afford toys like that! I'll be interested in hearing what they come in at.

 

[mike_l]

Fred,
I am really interested in this new toy! [] It will go well with the indexing plate I got from you. I'm looking forward to your updates.
Of course, I'm kind of like Lou, I don't have a clue as to what you and Mudder are talking about.

Mike L

 

[PenWorks]

Fred, put me down for your new toy when you get it done! []

 

[Fred in NC]

Thanks Anthony!

It will be a while. We will be working on the prototype this weekend, and next week. Then we need to test it before we build any production units. I would say about a month before we can ship. I will keep you posted.

 

[PenWorks]

Just makin sure I was at the top of the list ! No hurry, I have several types for dremal and fordom heads, so I think one of them should work whatever you come up with.
My main interest is doing 4/6/8 sided pens.

 

[fritzmccorkle]

any idea on what the price will be? i've been getting interested in the lathe wizard and was pointed here. i don't have the indexing wheel or anything. will there be a package available and will there be something that allows you to do spirals?
thanks,
fritz

 

[Fred in NC]

Fritz, it will be a few weeks before the carriage is ready. The indexing wheel kit is available separately, but of course you can order it along with the carriage.

Spirals are part of the plan. Not only that, you will be able to use your own pitches (number of spirals per inch, same as bolts).

I will post here when it is ready.

 

[dwilasnd]

Any news on availablitiy?

Dave

Originally posted by Fred in NC
<br />Some progress has been made. The carriage has been made to .003 tolerances, which is about the thickness of a piece of typing paper. The reason it is being built to high precision is that unlike a bowl turner, we work with very small pieces of wood. I want to be able to use router and engraving bits in sizes from 1/64" and up.

The driving screw is ACME 1/2" X 10 TPI. The carriage length, from bracket to bracket is 12". Longitudinal movement will be about 8". The wood parts that you see in the pic are only temporary for testing. They are being replaced with metal.

I am working on the first tool holder and in/out mechanism, which will hold a regular Dremel (current model available at most stores). The plate that will sit on top of the sliders can be customized to hold different rotary tools.

The first prototype should be ready in about 2 weeks. If all goes well, I will probably have a few ready in about 4 weeks.

<br />

 

[woodscavenger]

so....????? ......$$$$$$$$

 

[Fred in NC]

The carriage project has been put on hold until I have more time to work on it. That probably means a couple months. As it is the carriage is usable in the longitudinal axis. The original cross feed (in/out) is a bit too expensive for most pockets. I am working in a more inexpensive solution to make the setup affordable.

 

[wayneis]

Fred what would the cost be of one like you show here? I'm willing to pay for quality.

Wayne

 

[Chuck Key]

Originally posted by Fred in NC
<br />As it is the carriage is usable in the longitudinal axis. The original cross feed (in/out) is a bit too expensive for most pockets. I am working in a more inexpensive solution to make the setup affordable.

Mount a second carriage to the one shown at 90 degrees. On the second one shorten the leadscrew and use angle with shorter legs. Attach the Dremel or whatever to the second carraige. Possibably a quick fix for some.

I am going back to the shop now[]

Chuckie