What paint spray guns do you use? Anyone using high volume low pressure(hvlp)?
I know a lot of guys use hvlp restoring vintage wood working machines with excellent results, anybody using them for frames? I'm also interested in what guns are used that are 'affordable'(yeah, pretty vague, just not the high end commercial ones) for the sometime frame builder.
I was a frame painter for a bit in the 80s. I have a newer HVLP gun that I've done some automotive stuff with, the tip size seems to be crucial to getting the proper mist out of my set-up (mid quality gun and top shelf urethane enamels).
I will never use a mid-priced or cheaper gun so I don't have any advice as which one of those unacceptable guns are less objectionable. Customers expect top quality paint jobs from me and that begins with the equipment. However I do understand having a modest tight budget for a hobby so I'll pass on some general guidelines for buying a spray gun. It is possible to buy decent used top flight guns or get them on close out. The best ones are Sata from Germany and Iwata from Japan. They are engineered and manufactured to a higher standard that atomizes (puts into tiny droplets) paint better.
An HVLP gun is designed so that less paint is used. They can get a good finish but not quite a good as a non-HVLP gun. A rough average volume for one coat of paint on a bicycle frame is around 2 OZ with an HVLP gun and maybe it is 2 1/2 when using a standard gun. I use both. For the final clear I always use a standard gun as it flows out slightly better. In some states there are regulations so only HVLP guns are sold.
An HVLP gun is more sensitive to airline pressure and requires a regulator at the base of the gun. I always use a diaphragm type there because they don't give a sudden burst of paint when the trigger is first pulled like the more common needle type of regulator. Keep this extra cost in mind. Also always put a deposable filter on the end of your gun too.
Most spray guns are sold to auto body guys that need big cups so they don't have to interrupt their work to refill. At most all one needs for painting a frame is 6 OZ at one time so you definitely want to find a gun that uses those smaller cups. Otherwise those big things are more likely to be uncomfortable and bump into your work. You have to check and see what guns fit smaller cups. By the way it is possible to use an adaptor to fit small single use deposable cups from companies like 3M on any gun. But I would not want to use a $1 deposable cup for the small amounts needed for just a panel.
Speaking of fit it is important to me that the gun is comfortable in my hand. I would check how the feel before getting something. I have a smaller hand and the 300 series Iwatas are my favorite because of this. They are in-between a spot repair and full sized gun. Iwata quit making them but still have some in the pipe line. I bought a new one on close out at my paint jobber for $200 a year or two ago. Good guns average $300 to $500.
I always set my spray pattern to round. Some nice touch up guns are cheaper because they can't do a fan pattern (like the Sata Mini-jet 4). I need at least a trigger big enough for 2 fingers (some touch-ups are only 1 finger size).
I prefer a nozzle size of 1.3 or 1.4mm. Some bike frame painters prefer the smaller 1.0 size but absolutely I don't like that size at all. I can not get as good of a result with them. The bigger size does require more skill so you don't get runs.
Last edited by Doug Fattic; 05-23-12 at 06:47 AM.
Thank you very much Doug. I have a cheapo(real cheap, $25) Habor Freight hvlp that I will try on some junk frames soon, not really expecting much other than hoping it will be better than rattle can.
Correct me if I'm wrong, but the difference between the low end and mid-high is the higher has better and more reliable atomization. The lower end is more prone to "orange peel". $500 prices a lot of hobbyists out and you can correct orange peel with fine-grit sanding.
I don't think that a more expensive gun guarantees a "better" or an orange-peel free finish at all, that is the skill of the operator. If you set up the gun correctly, you can get excellent results with less than ideal equipment (I have), and that was my answer to the HVLP query. As for orange peel, it is a phenomena much more common to painting panels (evil cars) rather than tubes (bicycle frames) - I have painted both professionally many years ago but would defer to Doug... If you have to sand a top coat you have failed as a painter. You should be able to lay down a mist of material - atomized paint - in a perfectly uniform and perfectly smooth pattern, be it a fan pattern on a car or a spot pattern on a bike frame. Orange peel has to be introduced by the shear forces of the compressed air and paint mist sliding across wet paint. I will reiterate: In my experience the proper tip size is crucial using an HVLP gun.
Originally Posted by roburrito
A more expensive gun will be more consistent over many jobs and hold up to the rigors (lots of dismantling and cleaning) of the busy professional painter, you should avoid the cheap crap out there but there are some great values for the home enthusiast.