Author Topic: Re-Pimping the 7x12 minlathe. (Read 60066 times)

RotarySMP · « **on:** January 26, 2020, 10:48:37 AM »

I got a mini-lathe from Artec (a German brand), about 10-15 years ago. It is the generic lathe made by SIEG, but branded and sold by every man and his dog. it was the only machine tool I had as we had an inner city apartment, and the lathe in the corner of the balcony was the machine shop.
http://wrathall.com/Interests/machining/My_shed.htm
I did a lot of modding on it. Starting with the typical little stuff like swarf guard on the apron gears, and adding a carriage lock.
http://wrathall.com/Interests/machining/Carriage_lock.htm

Then on to some more extensive mods like the T-Slotted cross slide, which was very handy.
http://wrathall.com/Interests/machining/Carriage_lock.htm

It was quite quickly converted it to TurboCNC, which worked quite well. The canned cycles were really quite handy.

Since moving into a house with a basement machine shop, the 7x Minilathe has just lurked in the corner, except for being abused into turning wood on a couple of occasions.

I was never that happy with some of the harlf-arsed mods I did, and also got interested in doing a scraping project, so figured the little mini-lathe would be the perfect practice piece as it is nice and small and shouldnt take for ever.

Here is the first installment of the video log of re-modding it...

Mark

RotarySMP · « **Reply #1 on:** February 16, 2020, 04:11:38 PM »

I have made a fair bit of progress on the Minilathe.

Episode 2 - Still scraping

https://youtube.com/watch?v=-yFdCi35u_k

Episode 3 - Finishing the bed

https://youtube.com/watch?v=7MTHWuS5S8A

Episode 4 -

https://youtube.com/watch?v=-xdPNk6Fluw

Mark

Joules · « **Reply #2 on:** February 17, 2020, 02:42:04 AM »

Great series of videos, I particularly like the 3D printed lathe dog, look forward to seeing how that works out for you.

RotarySMP · « **Reply #3 on:** February 17, 2020, 05:11:48 AM »

Thanks Joules. My first thoughts were machining a steel lathe dog on the MAHO, but the 3D printer provides a way faster solution, for a one off problem. On another forum someone was wondering whether that Lap would work 3D printed as well.
Mark

Joules · « **Reply #4 on:** February 17, 2020, 05:46:16 AM »

Mmmm, many times I have used wooden internal laps, not sure I would trust the printed plastic direct, especially if it warmed up a bit. I have small bending rolls and would consider rolling a thin wall tube for cutting up, then epoxy the pieces to a 3D printed lap carrier. Get the best of both worlds, must give it a try. I recently started laser cutting fine emory paper and adding that to 3D printed profiles for polishing.

Regardless of all that, very much enjoying your journey with the Mini lathe.

RotarySMP · « **Reply #5 on:** February 17, 2020, 07:50:07 AM »

Thanks fo the encouragement. The whole video thing is much harder than I thought. Especially once you record yourself you find out how scatterbrained your thoughts are, and that rather than sounding like a TV announcer, you sound like a stoner

I need to make another lap for that test bar, and think it'll be a 3d print one and see if it is a complete or partial failure. Good point on the heat effects.
Mark

Joules · « **Reply #6 on:** February 17, 2020, 09:02:41 AM »

My major worry on a printed lap is not getting the scraper action a metal lap will have to clear slurry. Find out in a few hours when the first test lap comes off the printer.

Well being stoned explains how you can keep scraping for so long

RotarySMP · « **Reply #7 on:** February 17, 2020, 09:34:18 AM »

Scraping is kind of addictive. When is enough? when do you stop? it is all subjective, so you do "just one more pass" and then "just one more". Soon enough you arms and back are aching.
Mark

RotarySMP · « **Reply #8 on:** February 17, 2020, 02:12:33 PM »

Just tried out the plastic lathe dog. Worked very well.
Mark

Joules · « **Reply #9 on:** February 17, 2020, 05:03:58 PM »

Good news, another accessory added to the list of prints here.

RotarySMP · « **Reply #10 on:** February 23, 2020, 05:23:15 AM »

The fifth episode of this series is now up.

https://youtube.com/watch?v=BR6Xgl5DZqU

Mostly it covers making the #3 Morse test bar. Hope you enjoy it.
Mark

RotarySMP · « **Reply #11 on:** March 07, 2020, 05:33:30 PM »

I was out on a business trip and missed a week, but here is the 6th episode. Scraping in the head casting to align it to the bed. Went better than I expected, with one hiccup.

https://youtube.com/watch?v=UKql42-amdE

RotarySMP · « **Reply #12 on:** March 15, 2020, 09:38:39 AM »

Since the lathe bed was only as stiff as a wet noodle, I did a quick and dirty reinforcement.

https://youtube.com/watch?v=iplxnimaFSI

Mark

Joules · « **Reply #13 on:** March 17, 2020, 05:14:33 AM »

Interesting video Mark, do you plan to add a cover where the gap in the carriage exposes the ways. I see a path way for fine swarf getting under the saddle, but don't know how much clearance you have with the modified nut.

Brass_Machine · « **Reply #14 on:** March 17, 2020, 09:42:14 AM »

I'm late to the show... Now I have videos to binge watch!

Eric

Chuck in E. TN · « **Reply #15 on:** March 17, 2020, 12:10:48 PM »

Quote from: RotarySMP on February 17, 2020, 05:11:48 AM

Thanks Joules. My first thoughts were machining a steel lathe dog on the MAHO, but the 3D printer provides a way faster solution, for a one off problem.
Mark

Can you share the stl for the late dog, or post a picture, please?

Chuck

RotarySMP · « **Reply #16 on:** March 19, 2020, 03:53:50 AM »

Glad you are enjoying the series. I have attached the STL of the 20mm dog. The forum does not accept the extension .stl, so I renamed it to .txt, just save it and rename it back. The extra drive tab broke off when I used it.

Mark

nrml · « **Reply #17 on:** March 19, 2020, 07:41:25 AM »

Why don't you add a third leg between the base plate and the lathe bed to improve stiffness?

RotarySMP · « **Reply #18 on:** March 19, 2020, 04:34:32 PM »

Thanks for watching the video. It would still need a stiff base plate. Making and fitting a third leg would be a lot of work. If I was going to do a lot more work on bed stiffness I would be more likely to bury it in a big block of epoxy granite.

nrml · « **Reply #19 on:** March 19, 2020, 07:05:15 PM »

I was thinking on the lines of a simple block of steel or cast iron of suitable height bolted to the base plate and the gap between the bottom of the bed and the new leg filled with JB-weld or similar. A bit crude, but there will be some additional support to that thin span of bed without increasing the weight of the bed itself.

Epoxy granite would be good but you might be venturing into the zone where the minilathe is compromising your design rather than being a convenient skeleton for re-fleshing.

WeldingRod · « **Reply #20 on:** March 20, 2020, 10:49:35 AM »

Epoxy granite will get you in trouble with mis-matched thermal expansion!
Adding structure underneath and tying in with jb weld floated pads is a much better plan.

Sent from my SM-G892A using Tapatalk

RotarySMP · « **Reply #21 on:** March 20, 2020, 06:06:30 PM »

I am not going to do anything more than bolt it down to that slab of steel. E/G was just theory for this one. Looking at the theory, differential expansion is not really an issue in my basement. The temp range is very limited.

I just uploaded episode 8.

RotarySMP · « **Reply #22 on:** March 26, 2020, 11:21:02 AM »

Here is episode 9...

I am trying to up the frequency and the quality at the same time. Hope you enjoy it.
Mark

RotarySMP · « **Reply #23 on:** April 07, 2020, 06:14:51 AM »

Here is episode 10 of this continuing saga... enjoy.

https://youtube.com/watch?v=QdJcBxymCRM

Mark

RotarySMP · « **Reply #24 on:** April 12, 2020, 12:18:50 PM »

Continuing to polish this turd, episode 11 covers the close fitting gib I made for it.

https://youtube.com/watch?v=1tqLHFMwqx0

Mark

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Author Topic: Re-Pimping the 7x12 minlathe. (Read 60066 times)