By continuing to use this site, you agree to our use of cookies. Find out more

Member postings for PekkaNF

Here is a list of all the postings PekkaNF has made in our forums. Click on a thread name to jump to the thread.

<< First < Prev 1 2 3 4 5 Next > Last >>
Thread: A plastic valve
10/06/2011 09:22:54
Sweet!
 
Thank you for sharing this, very impressive.
 
I liked the pump, can you draw and publish it's principle. Great idea is onething - it's another idea to get it workking.
 
I'm in hardcore industry, but many of my friends are not, therefore it's interesting to swap stories sometimes and sometimes I got a little involved of putting same minded people together from completely different fields. Peristaltic pumps and pinch valves are neat.
 
Pekka
Thread: Threading Inserts
09/06/2011 17:25:15
Hi,
 
I can do external thread and most of time also a internal thread acceptable.
 
However, I'm having trouble with finer threads. I'm not confident that I'll get the threadfrom exactly right. I use partial form insert, plunge it straight (no rubbing), but even with all the initial external measurement, loupe + some eye balling + trying out with a nut and "close" enough I have this nagging feeling that it's not all that great.
 
I probably could afford thread gauges for few most used thread sizes, but the ones that gives me most trouble are typically something like M13*0,75!
 
What about wire method, would that get me out of trouble?
 
Old books recomend thread chasers to finnish up the work. Can you buy those anywhere? Probably I would be better of with simple HSS inserts shaped like carbide threading inserts.
 
Pekka
Thread: A plastic valve
09/06/2011 13:17:36
PTFE have it's uses, but it takes some understanding. Once I used it as a bearing AND brake. Had to turn OD to dimenssion, ID only to inser tool, primed PTFE cylinder and aluminium boss, added accelerator, glued them together (had to work fast thus jig and inser tool) and then turned ID to a dimenssion with one point internal tool.....
 
Tried different methods, but PTFE creeps and does not respect mechanical fasteners
 
It's not too difficult to dril/turn just to get workholding right or the dimenssions are down to tubes.
 
I liked your spool actuation! Sounds like stuff two molecularbiology scientists used to talk "we have to get this cooled dna to catalysista fast and then zap it with a lazer and then gather readings and hope they are not all over the walls" . They said that they wished they could have afforded me for the lab. And I tought I was badly paid, but they had to do they own tools and many componenest could have been agguired easier, but no-one come to think hiring somebody of a little industrial backgound.
 
Remember many syringes actuated with a stepper motor to give a accurate rate of material flow.
 
Many elastomer machining problems are fixed with right temperature. Often some cooling. Like freezing some rubber and then turning or drilling it. At -30C some plastics you can't regognice same. Or some high speed, on slow speed material seems viscous, but it "hardens" when you spin it fast and then pecdrill avoiding heating the tool tha leads to all the terible problems. Like a spider inside the table saw.
 
Pekka
07/06/2011 09:12:54
Heat is used to "smooth" edges of many plastics on many processes. This is ofcource counter productive here.
 
Maybe you first drilled the ports, then reamed spool hole, then insertted a flushing spool and purged the lines with suitable (particle loaded???) medium. Just maybe a drap of solvent and/or detergent. Then apropriate cleaning?
 
I'm not big on machining PTFE. I like POM, machines really nice. But sometimes you have to chose materials for medium. Did the PTFE ever creep or deform? You probably needed something to push or pull the spool
 
Pekka
Thread: Safety lamps for the lathe
11/05/2011 18:32:59
Posted by John Corden on 07/05/2011 19:05:44:
These might suit:
 
 
Very white light, stable gooseneck and no heat.
 
Edited to add: major dia of lamp is about 35mm. You can use the supplied base or fix the gooseneck to any convenient surface.
 
John

Edited By John Corden on 07/05/2011 19:08:40

Bought one of those with a clamp. Just to be "sure" I put it on for a breakfast. It worked three minutes. Very disappointed on chinese quality.
 
PekkaNF
Thread: Setting topslide to an angle
11/05/2011 18:29:35
Good. Now there method of turning the top slide, but how about getting it to a exact angle. I'll get it pretty close with morse tapper and TDI, but what about if the taper reference is miniscule?
 
But If I want to set very close to 8 decree for ER11 holder angle?
 
The ER collets I have are max ER 25 and I'm not convinced they are accurately clockked.
 
I probaly could use Haralod Hall method of two diameter discs of exact distance appart, but it really would excell on more shallow tapper.
 
Any other viable ways? I have tried to find a half decent "metric" sine bar, but haven't got any at my eyes.
 
Thanks,
PekkaNF
Thread: Removing needle roller bearings ?
04/05/2011 11:32:13
There is one trick I have used to get out stubborn bearing outer rings: Fix pipe or flange to bearing and tack weld. I admit that I have used this only few times when I have got nothing to loose, but it works surpricingly well.
 
Once there were no provision to pull out the outer race and and gearbox case was made out of aluminium...I tack welded few really small tacks - just to try it and the race come out just with a gentle pull when I tested the feel of the tacks.
 
I would gues that just few little zaps of mig might compress the thin needle roller bearing just enough to ease it out. Wet rag might keep the outside cool and prevent it from warping.
 
PekkaNF
Thread: Machinability v Mess v Finish.
06/04/2011 12:00:25
I have a bit of dilema:
 
Can't really find localy any free maching steel rods.
 
I have some tempering steel 34CrNiMo6 that I can turn, but I really don't enjoy drilling, reaming or taping it.. Other codes are: 4340 817M40 En24
 
I could buy these too:
Tempering steel. 42CrM04 W.Nr 1.7225 SIS 2244 Böhler V320
Cold work steel DIN 115CrV3 "Silver steel" max 220 HB

Which one is easier to thread/tap/drill with HSS?
 
PekkaNF
Thread: Building lathe/mill in cast of concrete?
06/04/2011 11:27:21
Hello,
 
I bet you are thinkking of casting normal rebar reinforced concrete structure.
 
Concrete can take a lof of compression and it is good in dampping among other properties. Although It shrinks much with the time. You could age it naturally before milling pads, you could try to find more stable concrete or you could make provisions for shrinkage.
 
Because of shrinkage it would be a bad idea to pour concrete inside of the metal "tube", far better idea would be to have iron structure outside and have concrete body on compression. Concrete really is pretty bad to machine, you need metal pads and plates that you can skim and level after curing and agigng the structure. In the industry often machine base plates are jacked straight over concrete sructure and then voids are filled with injection "epoxy". I'm pretty sure it has some filler.
 
I chekked some injection concretes that are available at the hardware stores, they expand first to counteract shrinkage. I'm not sure if this leads to more stable body.
 
See here some good info about frames and concrete core damping.
 
Then there is polymer concrete. This is rather different animal. If you think of a minimum possible amont of epoxy and maximum amount of rock in differet particle sizes - you are close.
 
This approach needs better process control and also materials tend to be more expensive. For a professional builder benefits are clear: More stable and fast production i.e. no concrete type of shrinkage.
 
Have fun. I have been toying with an idea of trying this to a small grinding machine.
 
PekkaNF

Edited By David Clark 1 on 06/04/2011 17:14:13

Thread: Tony Jeffree's Grinder letter in MEW175
16/03/2011 14:10:15
Poor car is exhausted trying to see pinout of D-15 connector?
 
PekkaNF
Thread: The mis-conception round bar is round
16/03/2011 07:57:45
Posted by Andrew Johnston on 15/03/2011 21:37:34:
PS: If anybody wants a 1m length of nominally 1/2" silver steel PM me and you can have it, if you collect it, otherwise it'll get recycled next time I go to the council tip.
I like 1/2" althoug I try not to mess with imperial measurement. 1/2 is fairly easy to turn/grind to nominal 12 mm and close to required tolerance.
 
Just never have got round buying one, because it's all metric here. I have turned some short pieces from 16 mm silver steel down to 12 mm.
 
PekkaNF
Thread: Tony Jeffree's Grinder letter in MEW175
15/03/2011 13:20:51
I foundTony Jeffree's letter funny, but not offensive at all.
 
I have got THE book, but not castings. I must addmit that I probably never get around building one, but it's an interesting book to read, and not at least because of the prosedures it has to cut some metal with style.
 
However, I think that while that humor is boud to attract some friendly fire, it will distract from the main thing: what is my need for a TC-grinder? I have tried to answer that question for myself and I have found that right now I'll rather manage with very primitive and limited grinder, that put time and space for all-singing all-dancing TC-grinder.
 
I understand that editor has to have a sustainable policies. But I still enjoy reading the letter.
 
PekkaNF
Thread: Klippfeld Lathes and milling machines
01/03/2011 13:39:10
Hello,
 
Went to visit Klippfeld (near Wiena, Austria) last friday. It was really small factory with a truck loads of lathe castings etc. Very small scale. Pretty much everything else seem to made on the premises, except motors, linear rails/runners and electronics. Lathes looked actually very sturdy in real life. Whole lot bigger than I tought of.
 
I went to see the milling machines. I saw only one small milling machine, they didn't have the bigger one on the display. The small one is too small for me and it looks like it's more of a drill than a mill. Pretty nice feel tought. Smalles cross table is small, bigger ones are more reasonable size.
 
Nearly 50% of the machines and parts under manufature were equipped with linear bearings during my visit.
 
If I were lookking for a western make model engineering plain bed lathe, I would have a second look on these ones. They seem to have very sound basic contruction. One model I checked briefly had all the normal necessities and was very rigid. Only one thing I didn't expect was that cross feed had 60 decree M12 instead of acme. There seemed to be good finnish on only those parts that had to mate, ohers we left as they come out of the machine. I prefer it, instead on someone "cleaning" with hand file and/or sandin paper/flap disc. Every control I tried had a very nice feel to it, very much better than the chinese made stuff. Running sound was very low level and pleasant..
 
Anyone using these? K-10 or F-10 or F-12?
http://www.klippfeld.at/index_en.html
 
PekkaNF
19/02/2011 20:50:11
Hello,
 
One day (hopefully soon) I'll be buying another lathe and a milling machine.
 
I probably would be better off with light ex-industrial machine, but I never find one decent one!
 
I have set my eyes on this Klippfeld, because they are still made in EU and apparently they do them on one location. The english in the site is even worse than mine, I really can't grasp the crux of the machines, but if I read them right, they look good. Shipping cost might limit my willinness to buy them, but I really have a soft spot on any Eropean made machine tool.
 
Has anyone have these lathes and particulary milling machines?
 
How do they compare?
 
I'll be going to Austria for a short thip and it looks like it would only be 15 km diversion.
 
PekkaNF
Thread: Notes on CNC Milling of 316 Stainless Steel
15/02/2011 09:52:01
Hello,
 
What mill did you use? Is it for hobby use or the to bring the bead on the table?
 
"I used two cutters; a 6mm three flute centre cutting uncoated endmill, and a 2mm four flute centre cutting TiALN coated endmill, both from Garr Tool.
 
Looking up Machinery's Handbook gave a surface speed of 200fpm for carbide in 316."
 
Solid carbide end mill needs to be run the hell of it:
http://www.gwschultz.com/information/speedAndFeeds.html

I'm not very familiar with these, but I have impression that HSS and solid carbide is of completely different animal. Carbide probably would do better with a rigid setup, machine and if the spindle can run it to the table. HSS probably wins on all other situations.
 
Probably not for SS, but I have heard that solid carbide cutters are used often without liquid, but blasted with copius amount of air.

PekkaNF
 
Thread: Tip build-up
02/02/2011 13:09:39
Someone really should biachslap me again! Carbide bit - cry out loud! I mean carbide insert, not carbide tipped tool lookin object, which only has ecological niche on taking skin off from mystery metal or cast iron.
 
Carbide insert please. Those shiny candy or blingy lookkin metal cutting objects!
 
If this mystery metal has carbide inclusions or other type of minor crap in it, HSS can't take it.
 
PekkaNF
02/02/2011 11:24:05
My first instinct would be to try coated (any coating for iron metals) carbide bit and run the heck out of it. Least 3*rpm you are using now. I probably would try pretty deep cut as well even on the expence of feed.
 
My reasoning is that more ofthen than not I have got rid of build-up by increasing the speed.
 
Another thing: Some HSS/work material combinations seem to more prone to "welding" due to HSS composition I guess....different tool material might help when geometry/speed/feed trinity does not manifest any appreciable improvement.
 
PekkaNF
Thread: Backlash - Steppers, Toothed Belts & Ballscrews
27/01/2011 19:49:18
First question is that does ballscrew has low enough lead and stepper (and controller) enough grunt to move that machine? Most of the time you will need gearing to gain enough power out of stepper. This will sacrifice speed, but it is evitable. Z-axis will typically exhaust any reasonable size stepper without gearing, You might think of using counterweight, but that would add more inertia and limit acceleration.
 
Good couplings and toothed belt drives are relatively rigid. There are straight below or spiral cut couolings that are essentially zero backlash and rigid. Ball screw bearings and their mounting to the frame is very important.
 
Limitting factors for a accuracy stability It's not only apparent play, but least equally flex, due to mounting and superstructure.
 
Also one important point is to understand that any manual mill is not made for CNC. Besides acme screw, least equally limiting factor is lack of linear bearings. Go easy. Go slow. And lube slide ways well.
 
PekkaNF
Thread: steam turbine and generator
19/01/2011 20:12:05
OT:
I found a picture of the motor here:
http://0.tqn.com/d/dogs/1/0/O/0/0/-/dyson-motor.jpg
It's middle of this page:
http://dogs.about.com/od/productreviews/fr/dysondc13animal.htm
I would love to know details of the motor and the bearings, but it looks (completely off hand) to me a bit strange that the simple armature winding on the picture would be any good of frequency of the SR motor of quoted speed.
EOT****
I found some comparison of different generator types used on (a LOT bigger) Microtrbines:
http://www.electrodynamics.net/documents/electrodynamics_power_gen2002.pdf


Casual look shows that layman is confronted with excitation problems and desingn complexities. This might make SR design less appealing.
Is there any other alternative to produce a lttle electricity on turbine lookking structure? Turbines don't scale well. Anything in the domain of rotary piston or air vane motor?
I have tought of cannibalizing a chep pencil grinder or a small die grinder.
Or it really HAS to be TURBINE? Oh. dear!
PekkaNF
Thread: Electric Motor Noise
17/01/2011 19:01:20
Pretty sure buyer on the mfg side has bought the bearings on price only. Electric motor bearings used to be of tighter tolerance than for agricultural use. Many easter mfgs will print on the box whatever and lot of buyers would buy on first few digits right on the bearing code anyway. It's really amazing difference what bearing does.
 
Seriously. I heard one sick motor and everything else was correct (even the bearing type) and OEM manufacturer had it right. However  the manufacturer of the gear unit had failed on pre paint wash = most of bearing grease was lost and replaced with solvent and detergent! After shipping it over the pond and keeping it in  the ware house for a year, had bearings heading south in no time.....
 
I'm pretty sure you tested it without load. Have it coast down and there you have bearing sounds only....laminations make sound only when powered up. If the sound comes from lamination....ditch it.
 
PekkaNF
<< First < Prev 1 2 3 4 5 Next > Last >>
Magazine Locator

Want the latest issue of Model Engineer or Model Engineers' Workshop? Use our magazine locator links to find your nearest stockist!

Find Model Engineer & Model Engineers' Workshop

Sign up to our Newsletter

Sign up to our newsletter and get a free digital issue.

You can unsubscribe at anytime. View our privacy policy at www.mortons.co.uk/privacy

Latest Forum Posts
Support Our Partners
cowells
Sarik
MERIDIENNE EXHIBITIONS LTD
Shopping Partners
Subscription Offer

Latest "For Sale" Ads
Latest "Wanted" Ads
Get In Touch!

Do you want to contact the Model Engineer and Model Engineers' Workshop team?

You can contact us by phone, mail or email about the magazines including becoming a contributor, submitting reader's letters or making queries about articles. You can also get in touch about this website, advertising or other general issues.

Click THIS LINK for full contact details.

For subscription issues please see THIS LINK.

Digital Back Issues

Social Media online

'Like' us on Facebook
Follow us on Facebook

Follow us on Twitter
 Twitter Logo

Pin us on Pinterest

 

Donate

donate