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View Full Version : Homemade 4 1/2 inch "Model Makers Lathe"



Serceflyer
10-27-2007, 11:16 PM
Has anyone every heard of this project:

http://www.vintageprojects.com/machine-shop/lathe-modelling1.pdf

I think I understand the drawings and I'm currently trying figure out how to bevel the 30 deg "dovetail" edges.

But, I'm puzzeled by the use of metal dowels. What size hole would you drill for 1/8" dowels? Are the dowels pressed in or tapped with a hammer?

Thanks,
George

mechanicalmagic
10-27-2007, 11:31 PM
Has anyone every heard of this project:

http://www.vintageprojects.com/machine-shop/lathe-modelling1.pdf

I think I understand the drawings and I'm currently trying figure out how to bevel the 30 deg "dovetail" edges.

But, I'm puzzeled by the use of metal dowels. What size hole would you drill for 1/8" dowels? Are the dowels pressed in or tapped with a hammer?

Thanks,
George

George,

Normally dowel pins are pressed into one side that has been reamed to slightly undersize.
The other side is reamed to slightly oversize. Allowing the pin to accurately align.

dp
10-27-2007, 11:34 PM
Hmmm - I just learned out to make a miter sander with my cut-off saw.

oldtiffie
10-27-2007, 11:48 PM
George,

Normally dowel pins are pressed into one side that has been reamed to slightly under-size.
The other side is reamed to slightly oversize. Allowing the pin to accurately align.

Hi mechanicalmagic.

I don't know about "now" but when I was on die-work etc. and anything that needed to aligned and re-aligned, we used to get "stepped" dowels that had one part/end a light press fit into a standard reamed hole and the other end a very precise "location" (fine "push" or light "push") fit IIRC.

This only required that only one reamed hole was required - both "mating" parts were clamped together for the "drill and ream" part then freed and the
"larger" end of the dowel pushed/pressed into one part of the job that it was to remain in. It was essential,that the dowel be "dead square" before it was pressed in as it could "catch" or "gall" and that was a problem.

If possible, if access to the "fixed" dowel for removal is difficult or if it is in a "blind" hole. It will assist in any future removal of the dowel if a hole is drilled from the bottom of the dowel hole (hole to match appropriate "pin punch/s) for easier removal - with a pin punch and hammer etc.

I hope this helps.

IOWOLF
10-28-2007, 07:46 AM
Wow, I found my next project.:rolleyes:

I suppose in the 50's it was the hot setup.

SGW
10-28-2007, 07:54 AM
Check a big catalog like MSC www.mscdirect.com and you should find "dowel pin size" reamers that are + or - a couple tenths from nominal. You may also see over- and undersize dowel pins.

My understanding of how it's supposed to work more or less agrees with mechanicalmagic's. Drill/ream one side so it's a suitable press fit for the dowel pin, and ream the other side slightly larger so the dowel pin will slide in with no slop, for alignment, but be easily removable. If possible you'd probably want to drill/ream through both at the smaller diameter, for best alignment, then ream the larger side for clearance.

You'll need to pick and choose reamer and dowel pin diameters to get a combination that works for what you're trying to do.

Oldtiffie's stepped dowels, if you could find any, would be another way of doing it. Also take note of his discussion of blind holes and later dowel removal. Through-drilling and reaming simplifies life, if it can be arranged.

Serceflyer
10-28-2007, 11:02 AM
IOWOLF,

Are you going to "let the lathe build itself?" I've read the article a few times. Once you get the headstock set up, you are supposed to drill all the dowel holes, etc with your new mini headstock.

I wonder if this little machine can really turn some accurate small pieces?

George

IOWOLF
10-28-2007, 05:28 PM
IOWOLF,

Are you going to "let the lathe build itself?" I've read the article a few times. Once you get the headstock set up, you are supposed to drill all the dowel holes, etc with your new mini headstock.

I wonder if this little machine can really turn some accurate small pieces?

George

You are friggin' kidding, right?:D

I have a complete machine shop,Why would I want that POS?

You guys Have to learn about the smileys.:rolleyes:

BadDog
10-28-2007, 06:11 PM
I can see the alure of building your own. I've built some of my stuff, that in retrospect (or even predicted but ignored) would make more sense to buy. However, even if I had a need to build my own, I think I would start with a cheap (cheaper used and just as good for the purpose!) import lathe. Generally considered kits anyway, the castings are usually decent (check, some are crap with bondo filled voids, but most are ok as far as I've seen) and offer a much better starting point for headstock/bed/tail/saddle than what you'll get with angle iron fabrications. The HF 8x18 would actually be near ideal for this I think. External gears and a simple but (relatively) beefy construction. Then, upgrade the bearings, rebuild parts that are inferior, scrape for bearing/alignment, and in the end have a MUCH better little lathe for far, FAR less work (and possibly less money in the long run).

J Tiers
10-28-2007, 08:17 PM
I have a complete machine shop,Why would I want that POS?

At some time, one may (or not) get the urge to see what can be made "from nothing", without machine tools.

It's one of those chicken and egg things, solved by MAKING the egg........

Personally, knowing I could probably do it would be enough for me, but I can at least understand the motivation.

If I really wanted yo do some such thing, I'd want to do it more along the lines of what Maudslay did. As that is a lot of work, and my motivation is low, I've not done it.

S_J_H
10-28-2007, 08:28 PM
baddog., yes and no. That old lathe design being talked it is WAY past it's day.

Modern linear rails and vfd drives are pretty cheap now. I have a 9x20 and my recently bought very old Artisan as well. The cnc bench lathe I built is smaller than my 9x20 which is heavily modified but will out perform it in every way imaginable. The 90 year old Artisan makes the 9x20 look like a kids toy in every aspect.
If one was to build a lathe from scratch IMHO it should be a cnc machine usng modern linear rails and maybe a vfd drive. If you wanted to build a manual lathe, then yes it'll be hard to beat even the worst of the import lathes. The 8x12 and 8x14 are not to bad. Still far from anything one would consider heavy duty but they are a step above the 9x20's. These import machines do a good job of making what the eye can see look decent. They give the ways a nice ground surface for example. When you take them apart you get to see how they were really built! They are getting better though I admit. The x3 mills are not to bad for instance.
Steve

steverice
10-28-2007, 09:00 PM
looks like a fun project, alot of good learning to be done on such a basic project

IOWOLF
10-29-2007, 06:25 AM
looks like a fun project, alot of good learning to be done on such a basic project

If you are an amateur, to some it's a waste of time.:rolleyes:

Serceflyer
10-29-2007, 10:51 PM
I already have a lathe, so this is more of a fun philosophical project. I've always been amazed by Maudslay and others who created incredible accuracy with machine tools made by hand.

So that's the challenge with this project: Can the lathe build itself? Can this little tool actually turn a good piece?

G

Evan
10-30-2007, 08:26 AM
So that's the challenge with this project: Can the lathe build itself? Can this little tool actually turn a good piece?

Keep in mind that a watchmaker's lathe is operated using hand held tools. It's the operator that mainly determines what the lathe can do. All that a basic lathe needs to do is hold the work and spin it next to a tool rest.

SHADOW
10-30-2007, 08:55 AM
It reminds me of a book I have "Building a small Lathe", by L.C. Mason,Model and Allied Publications, 1977. IIRC, Mr. Mason was a writer and model engineer who contributed to Model Engineer Magazine in the time period of E.T. Westbury and G. H. Thomas, and writes similarly style to those.

The lathe was built of precision ground stock and included backgearing, screwcutting gear, and indexing attachment. He states in another lathe he built he filed the crosslide dovetails and used a 60 degree bevel gauge to check frequently and had satisfactory results. He used a 3 1/2" lathe to build the one in the book and gives he reasoning for building it.

In the introduction he states, "When it comes to the final assembly of the finished components, all the fits and locations are adjustable for the sake of accuracy of the finished job. The final accuracy is dependent on the amount of care you are prepared to take over it."

It seems the last sentence has remained appropriate from the bow propelled turns to the present electronic era.