Press fit fasteners

[beatnik]

Tired of the chassis options available on the market I have started to make my own.

I have found some local shops to laser cut and bend sheet metal, but they are not equipped with machines for press-fit fasteners.
Since they would have to fit them manually, they recommended me to get a manual press and fit the fasteners myself, in order to save costs.

I tried fitting the inserts with a pillar drill I have but it clearly doesn't have enough force so I will need to get a dedicated press but I am unsure on what to choose.

THIS is the main kind of insert I will be using and the chassis material is 1.5mm mild steel.

I have attached a section of the PEM inserts catalog that lists the required force for fitting the inserts, the range is very wide and from what I can see it really affects the price of the press, I can get a decent quality 5kN press for about 100 euro, but a 25kN one is over 500 euro !

Main thing I am wondering is if the smaller press could do the job with just a bit more elbow grease ?

There are also some low cost pneumatic press sold from China like THIS but the force is specified at 200kG so a lot inferior to what the insert datasheet recommends.

An interesting bonus that could potentially come with a pneumatic machine is the ability of punching M3 countersunk holes instead of making them with a rotary tool. But I have no idea of the force needed for this job.

Any insight or recommendations about this subject would be very welcome.

 

[Newmarket]

I'd advise against trying to bodge the insertion force on these. Seen quite a few of these fail.

 

[beatnik]

Avoid bodging is the motive of my questions

 

[gyraf]

Perhaps use threaded rivets - they're simple to insert with the right tool, and they come in quite a few different styles and materials:

https://www.aliexpress.com/item/1005005402340084.html
and

https://www.aliexpress.com/item/1005004630494352.html
/Jakob E.

 

[beatnik]

I been using those so far, but there are a couple of drawbacks. The hole needs to be countersunk which requires extra time and the increased length of the fastener can be an impediment for mounting certain components within the chassis.

Anyway the actual plan is to use other kinds of press fit fasteners as well, like hex standoffs and studs. So I should really get some kind of press.

I have found THIS on eBay which despite the age looks well made and should have quite some power, the owner said he could punch 8mm holes in 0.7mm mild steel.
What do you think ?

 

[Newmarket]

0.7 mm mild steel seems pretty thin to me ? Or am I out of line with common usage on that ?

 

[Philbo King]

Tired of the chassis options available on the market I have started to make my own.

I have found some local shops to laser cut and bend sheet metal, but they are not equipped with machines for press-fit fasteners.
Since they would have to fit them manually, they recommended me to get a manual press and fit the fasteners myself, in order to save costs.

I tried fitting the inserts with a pillar drill I have but it clearly doesn't have enough force so I will need to get a dedicated press but I am unsure on what to choose.

THIS is the main kind of insert I will be using and the chassis material is 1.5mm mild steel.

I have attached a section of the PEM inserts catalog that lists the required force for fitting the inserts, the range is very wide and from what I can see it really affects the price of the press, I can get a decent quality 5kN press for about 100 euro, but a 25kN one is over 500 euro !

Main thing I am wondering is if the smaller press could do the job with just a bit more elbow grease ?

There are also some low cost pneumatic press sold from China like THIS but the force is specified at 200kG so a lot inferior to what the insert datasheet recommends.

An interesting bonus that could potentially come with a pneumatic machine is the ability of punching M3 countersunk holes instead of making them with a rotary tool. But I have no idea of the force needed for this job.

Any insight or recommendations about this subject would be very welcome.

A riv-nut tool might be an easier way.

https://www.boellhoff.com/us-en/pro...ind-rivet-nuts-and-rivstud-blind-rivet-studs/
Oops ninja'd by Gyraf...

 

[S.Samuelsson]

Hi.

I have found THIS on eBay which despite the age looks well made and should have quite some power, the owner said he could punch 8mm holes in 0.7mm mild steel.
What do you think ?

That punching capacity sounds rather weak to me, that kind of a machine should be able to do much, much better.
Or the pic lies more than a thousand words, and the press is a tiny one .
I'm not a big fan of round columns in any shop machines, but on that price range any other kinds rarely exist.
A round column doesn't matter that much if You're just swaging/pressing fittings, but any drift or bending when punching holes will dull the tools in a blink of an eye.

On the positive side, from the pics it looks like it can be operated both manually and pneumatically?
While pneumatically operated machines are nice for larger production, those require a foot operated valve, pressure-/flow regulator and of course, pressurized air, pumping the price up if You don't have 'em already.

There is no actual standard on the tooling either, so what ever You decide to get, make sure that the available tooling can be adapted easily onto the end of the tool head.
Of course, if You or a friend of Yours have a lathe or an access to one, life gets much easier.

Regards,
Sam

 

[beatnik]

The seller said the piston is 8cm diameter and there is the multiplier at the front.
From a rough calculation (thanks ChatGPT) using the piston diameter 8cm and 8bar pressure the resulting force is about 40kN which would be perfectly adequate for what I need according to the inserts datasheet.
Now I am not sure how the multiplier would affect the calculation, since the diameter of that part seems a lot smaller than the actual piston.

I only need the machine to press fit fasteners, but it would be a great bonus if it could also punch M3 countersunk holes so I don't need to use the rotary tool.
I don't need to punch holes as I will get that done with laser cutting.

I already have a large industrial compressor and a variety of manometer and pipes and connectors coming from a factory clearance so I don't think I will have to spend a lot in the additional parts and installation.
The main thing would making the dies and anvils for the various inserts. Machinists are pretty expensive around here.

I really think I should pull the trigger on this and worst case if it cannot get the job done return it to the seller since he lives only a couple hours away.

The throat is only 14.5cm so I would not be able to place inserts say at the center of the chassis but I think I could live with that.

 

[beatnik]

I already have more than one fabricator that can do the job. I would like to have the option to fit the inserts by myself for mainly three reasons :

- save costs - I can just get the fabricator to laser cut parts, I fit the inserts (and make the countersinks as well) and give them back the parts for bending. The fabricator is literally 5min walk from my lab

- quickly making prototypes - I make one offs and these jobs have high setup costs so if for example I have different PCBs to fit in the chassis, I could quickly drill the chassis and fit the standoffs based on the project requirements

- have fun

I am not surprised that a UK customer is coming to you for a one-off project. I lived in the UK for several years and I have always struggled to find businesses that are keen to work on low volume orders. Everybody wants to charge a premium price for setup fees and that discourages any hobbyist or small scale manufacturer. It feels like if you aren't the NASA or the MOD you cannot get anything done.
Italy is a lot better on that front but if you like DIY, then why not ?

 

[2nickel]

I have an 1-ton arbor press (Harbourfreight #59766 US$70) to fit PEMs for #8 nuts into sheet aluminum. Works great, I will try a #4 and #6 into mild steal later and report back. E

 

[2nickel]

I just tried it into 1.2mm mild steel. #4 and #6 worked well. #8 needed to be done in 2 steps as the thread barrel is 1.8mm long but it worked, with brute force. I do not see a problem using 1,5mm mild steel, but I would not do it for mass production. E

 

[zamproject]

@MidnightArrakis ...

Is it possible that all of your post don't look like advert .... with [BOLD] and bigger text size than anybody else ???

(sorry to the OP and others for off topic...)

 

[MidnightArrakis]

Is it possible that all of your post don't look like advert .... with [BOLD] and bigger text size than anybody else ???

[Is it possible that all of your post don't look like advert] -- I am -- NOT -- advertising ANYTHING!!! other than offering some designing assistance, should they want it.


[with [BOLD]] -- Of which I am using purely as a means to add emphasis!!! Since my rather ancient background was originally in "Journalism", the use of BOLD text is commonly used to express and/or place emphasis onto either a word or a phrase. You and the other members of this forum are probably not acquainted with being aware of that. I do know that many of you (younger) members don't like it!!!

[and bigger text size] -- My using the 18-point font-size versus the default 15-point font size that this forum uses is simply done as a courtesy and favor to the many over-50 and over-70 years old members on this forum to make it somewhat easier to read. While I happen to be using a 34" ultra-high-resolution monitor setup to enlarge the text in this forum, I am also well aware that most other people are using monitors typically within the 15-inch to 22- and 24-inch range, so I know that the 15-point font can be somewhat difficult to readily read. I am merely trying to make things easier for the older folks on here. I, myself, will become 75-years old much too soon this year, so I know how much difficulty that aging eyes can have when attempting to read small-sized text on a computer monitor or a cellphone screen.

/

 

[Brian Roth]

Nearly 70 year old eyeballs here looking at 24" monitor. I have Firefox "set" for "120% zoom level" for this....and other....forums I read.

 

[MidnightArrakis]

Nearly 70 year old eyeballs here looking at 24" monitor. I have Firefox "set" for "120% zoom level" for this....and other....forums I read.

>>>>>>>>> Nearly 70 year old eyeballs here looking at 24" monitor <<<<<<<<<



>> HERE'S LOOKIN' AT CHA!!!

/

 

[beatnik]

In any case.....a part of my main reason for responding to your posting was because your use of the CLS nuts may not necessarily be the correct nut for your application. I didn't delve into the criteria and/or parameters of the SMPS nuts that I suggested, but my general thinking was that perhaps the SMPS nuts -- may -- better fall within the force parameters of the equipment that you already have and, therefore, would be better suited for your use. That's all.....

SMPS doesn't come in M4 size.
M3 still needs 8kN insertion force Vs 11 / 15 kN of the CL series

I don't have any suitable tool already that's why I started the conversation.
Since I need to spend on a press I guess I should get one that can do also the higher profile nuts.

I really worry a hand press could become too much of an headache and result in messed up parts... Also I am looking to insert about 140 nuts for the first run of chassis (plus any studs that could go on the bottom plate for mounting PCBs)
I don't go to the gym and osteopaths are very expensive around here...

 

[S.Samuelsson]

Hi.

Now I am not sure how the multiplier would affect the calculation, since the diameter of that part seems a lot smaller than the actual piston.

Hard to judge from the pic, but I have a hunch that it won't affect it at all.
Assuming of course that the hand crank boss looking piece is actually for that purpose.
The piston rod and the pinol most likely have the same rack teeth Modul, and the hand crank gear just reverses the direction of the force.

I only need the machine to press fit fasteners, but it would be a great bonus if it could also punch M3 countersunk holes so I don't need to use the rotary tool.
I don't need to punch holes as I will get that done with laser cutting.

In that case, consult the laser cutter about that need beforehand.
The reason is that laser tends to microharden the cut surface with even certain mild steel varities, so parameter and/or material optimization may be needed if the holes are to be threaded or otherwise worked afterwards.

The main thing would making the dies and anvils for the various inserts.

Yes, hopefully the seller of the press can also sell You some, because even though making those is pretty straight forward on a lathe...

Machinists are pretty expensive around here.

That makes it always rather expensive if there's no lathes around.
But, machinists are expensive everywhere, the trick is to have something to trade for their time and expertise .

I really think I should pull the trigger on this and worst case if it cannot get the job done return it to the seller since he lives only a couple hours away.

Agreed, I for one don't see any reason why it wouldn't get the job done though.
And in the best case scenario, You may be able to test the press before buying.
It will require some maintenance at some point, but unlike for the modern equipment from the far east, I'd willing to bet that You can still get spare- and maintenance parts for it when the need arises.

The throat is only 14.5cm so I would not be able to place inserts say at the center of the chassis but I think I could live with that.

The shallow throat always restricts things with this kind of machines, but careful pre-planning usually takes care of that.
And the odd insert or post that can not be pressed with the machine, can always be done by hand if the need arises.

Doubling the throat capacity would probably at least quadruple the weight and the cost.

- save costs - I can just get the fabricator to laser cut parts, I fit the inserts (and make the countersinks as well) and give them back the parts for bending. The fabricator is literally 5min walk from my lab

- quickly making prototypes - I make one offs and these jobs have high setup costs so if for example I have different PCBs to fit in the chassis, I could quickly drill the chassis and fit the standoffs based on the project requirements

IMO excellent reasons for buying Your own equipment rather than outsourcing the job.

Since I need to spend on a press I guess I should get one that can do also the higher profile nuts.

Definitely.
And even though You don't need to punch any holes ATM, possibility for that kind of a need should be kept in mind also.
The more versatile the tool is, the better.
Buy once, cry once etc.
IME/IMO anyway.

I really worry a hand press could become too much of an headache and result in messed up parts... Also I am looking to insert about 140 nuts for the first run of chassis (plus any studs that could go on the bottom plate for mounting PCBs)

In that case, I for one can't see outsourcing as a viable plan.
And also speaking from personal experience, a pneumatic or hydraulic action is a must, cranking the handle while balancing the workpiece with the other will get very old, very fast.

Regards,
Sam

 

[beatnik]

In that case, consult the laser cutter about that need beforehand.
The reason is that laser tends to microharden the cut surface with even certain mild steel varities, so parameter and/or material optimization may be needed if the holes are to be threaded or otherwise worked afterwards.

Good point, I did not consider that. I am gonna be using zinc plate steel for the chassis body so will point this out to the fabricator.

Totally get the other points you made, thanks a lot for your valued contributions.

To me.....it sounds as though things have not been too well thought out beforehand!!!

To be honest I think either you are missing the point of what I am trying to do, or perhaps you are mainly interested in spam advertising your services, like you do on any thread where similar topics are discussed. Thanks anyway

 

[beatnik]

I actually managed to find a datasheet for the press sold on ebay.
The working force is listed as 250kg.
If I am using this formula to convert into kN
Force(kN)=(Mass(kg)×Acceleration due to gravity(m/s^2)) / 1000
This produces a force of 2.45kN which is way below the requirements for any of the threaded inserts I would like to use.
Unless I am missing something ?